1 | #!/usr/bin/env python |
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2 | """Polygon manipulations |
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3 | |
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4 | """ |
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5 | |
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6 | |
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7 | #try: |
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8 | # from scipy import Float, Int, zeros, ones, array, concatenate, reshape, dot |
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9 | #except: |
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10 | # #print 'Could not find scipy - using Numeric' |
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11 | |
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12 | from Numeric import Float, Int, zeros, ones, array, concatenate, reshape, dot, allclose |
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13 | |
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14 | |
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15 | from math import sqrt |
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16 | from anuga.utilities.numerical_tools import ensure_numeric |
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17 | from anuga.geospatial_data.geospatial_data import ensure_absolute |
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18 | |
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19 | def point_on_line(point, line): |
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20 | """Determine whether a point is on a line segment |
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21 | |
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22 | Input: |
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23 | point is given by [x, y] |
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24 | line is given by [x0, y0], [x1, y1]] or |
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25 | the equivalent 2x2 Numeric array with each row corresponding to a point. |
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26 | |
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27 | Output: |
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28 | |
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29 | """ |
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30 | |
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31 | point = ensure_numeric(point) |
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32 | line = ensure_numeric(line) |
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33 | |
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34 | |
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35 | res = _point_on_line(point[0], point[1], |
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36 | line[0,0], line[0,1], |
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37 | line[1,0], line[1,1]) |
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38 | |
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39 | return bool(res) |
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40 | |
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41 | |
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42 | |
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43 | |
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44 | |
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45 | def intersection(line0, line1): |
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46 | """Returns intersecting point between two line segments or None (if parallel or no intersection is found) |
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47 | |
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48 | Inputs: |
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49 | line0, line1: Each defined by two end points as in: [[x0, y0], [x1, y1]] |
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50 | A line can also be a 2x2 numeric array with each row corresponding to a point. |
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51 | |
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52 | |
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53 | Output: |
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54 | Point [x,y] or None. |
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55 | |
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56 | If line extensions intersect outside their limits, None is returned as well. |
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57 | |
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58 | """ |
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59 | |
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60 | # FIXME (Ole): Write this in C |
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61 | |
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62 | line0 = ensure_numeric(line0, Float) |
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63 | line1 = ensure_numeric(line1, Float) |
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64 | |
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65 | x0 = line0[0,0]; y0 = line0[0,1] |
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66 | x1 = line0[1,0]; y1 = line0[1,1] |
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67 | |
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68 | x2 = line1[0,0]; y2 = line1[0,1] |
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69 | x3 = line1[1,0]; y3 = line1[1,1] |
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70 | |
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71 | denom = (y3-y2)*(x1-x0) - (x3-x2)*(y1-y0) |
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72 | |
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73 | #print 'denom', denom, line0, line1 |
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74 | if allclose(denom, 0.0): |
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75 | # Lines are parallel |
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76 | return None |
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77 | else: |
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78 | u0 = (x3-x2)*(y0-y2) - (y3-y2)*(x0-x2) |
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79 | u0 = u0/denom |
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80 | |
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81 | u1 = (x2-x0)*(y1-y0) - (y2-y0)*(x1-x0) |
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82 | u1 = u1/denom |
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83 | |
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84 | x = x0 + u0*(x1-x0) |
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85 | y = y0 + u0*(y1-y0) |
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86 | |
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87 | assert allclose(x, x2 + u1*(x3-x2)) |
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88 | assert allclose(y, y2 + u1*(y3-y2)) |
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89 | |
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90 | # Check if point found lies within given line segments |
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91 | if 0.0 <= u0 <= 1.0 and 0.0 <= u1 <= 1.0: |
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92 | # We have intersection |
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93 | |
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94 | # Need tolerances if going ahead with this check |
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95 | #msg = 'Algorithm error. Intersection was detected but point (%f, %f) does not lie ' %(x,y) |
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96 | #msg += 'on line0: %s' %(line0) |
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97 | #assert point_on_line([x, y], line0), msg |
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98 | #msg = 'Algorithm error. Intersection was detected but point (%f, %f) does not lie ' %(x,y) |
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99 | #msg += 'on line1: %s' %(line1) |
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100 | #assert point_on_line([x, y], line1), msg |
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101 | |
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102 | return [x, y] |
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103 | else: |
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104 | return None |
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105 | |
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106 | |
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107 | def is_inside_polygon(point, polygon, closed=True, verbose=False): |
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108 | """Determine if one point is inside a polygon |
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109 | |
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110 | See inside_polygon for more details |
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111 | """ |
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112 | |
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113 | indices = inside_polygon(point, polygon, closed, verbose) |
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114 | |
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115 | if indices.shape[0] == 1: |
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116 | return True |
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117 | elif indices.shape[0] == 0: |
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118 | return False |
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119 | else: |
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120 | msg = 'is_inside_polygon must be invoked with one point only' |
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121 | raise msg |
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122 | |
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123 | |
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124 | def inside_polygon(points, polygon, closed=True, verbose=False): |
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125 | """Determine points inside a polygon |
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126 | |
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127 | Functions inside_polygon and outside_polygon have been defined in |
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128 | terms af separate_by_polygon which will put all inside indices in |
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129 | the first part of the indices array and outside indices in the last |
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130 | |
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131 | See separate_points_by_polygon for documentation |
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132 | |
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133 | points and polygon can be a geospatial instance, |
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134 | a list or a numeric array |
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135 | """ |
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136 | |
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137 | #if verbose: print 'Checking input to inside_polygon' |
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138 | |
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139 | try: |
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140 | points = ensure_absolute(points) |
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141 | except NameError, e: |
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142 | raise NameError, e |
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143 | except: |
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144 | # If this fails it is going to be because the points can't be |
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145 | # converted to a numeric array. |
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146 | msg = 'Points could not be converted to Numeric array' |
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147 | raise msg |
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148 | |
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149 | try: |
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150 | polygon = ensure_absolute(polygon) |
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151 | except NameError, e: |
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152 | raise NameError, e |
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153 | except: |
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154 | # If this fails it is going to be because the points can't be |
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155 | # converted to a numeric array. |
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156 | msg = 'Polygon %s could not be converted to Numeric array' %(str(polygon)) |
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157 | raise msg |
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158 | |
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159 | if len(points.shape) == 1: |
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160 | # Only one point was passed in. Convert to array of points |
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161 | points = reshape(points, (1,2)) |
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162 | |
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163 | indices, count = separate_points_by_polygon(points, polygon, |
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164 | closed=closed, |
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165 | verbose=verbose) |
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166 | |
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167 | # Return indices of points inside polygon |
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168 | return indices[:count] |
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169 | |
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170 | |
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171 | |
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172 | def is_outside_polygon(point, polygon, closed=True, verbose=False, |
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173 | points_geo_ref=None, polygon_geo_ref=None): |
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174 | """Determine if one point is outside a polygon |
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175 | |
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176 | See outside_polygon for more details |
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177 | """ |
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178 | |
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179 | indices = outside_polygon(point, polygon, closed, verbose) |
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180 | #points_geo_ref, polygon_geo_ref) |
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181 | |
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182 | if indices.shape[0] == 1: |
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183 | return True |
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184 | elif indices.shape[0] == 0: |
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185 | return False |
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186 | else: |
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187 | msg = 'is_outside_polygon must be invoked with one point only' |
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188 | raise msg |
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189 | |
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190 | |
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191 | def outside_polygon(points, polygon, closed = True, verbose = False): |
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192 | """Determine points outside a polygon |
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193 | |
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194 | Functions inside_polygon and outside_polygon have been defined in |
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195 | terms af separate_by_polygon which will put all inside indices in |
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196 | the first part of the indices array and outside indices in the last |
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197 | |
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198 | See separate_points_by_polygon for documentation |
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199 | """ |
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200 | |
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201 | #if verbose: print 'Checking input to outside_polygon' |
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202 | try: |
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203 | points = ensure_numeric(points, Float) |
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204 | except NameError, e: |
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205 | raise NameError, e |
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206 | except: |
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207 | msg = 'Points could not be converted to Numeric array' |
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208 | raise msg |
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209 | |
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210 | try: |
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211 | polygon = ensure_numeric(polygon, Float) |
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212 | except NameError, e: |
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213 | raise NameError, e |
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214 | except: |
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215 | msg = 'Polygon could not be converted to Numeric array' |
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216 | raise msg |
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217 | |
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218 | |
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219 | if len(points.shape) == 1: |
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220 | # Only one point was passed in. Convert to array of points |
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221 | points = reshape(points, (1,2)) |
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222 | |
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223 | indices, count = separate_points_by_polygon(points, polygon, |
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224 | closed=closed, |
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225 | verbose=verbose) |
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226 | |
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227 | # Return indices of points outside polygon |
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228 | if count == len(indices): |
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229 | # No points are outside |
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230 | return array([]) |
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231 | else: |
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232 | return indices[count:][::-1] #return reversed |
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233 | |
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234 | |
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235 | def in_and_outside_polygon(points, polygon, closed = True, verbose = False): |
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236 | """Determine points inside and outside a polygon |
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237 | |
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238 | See separate_points_by_polygon for documentation |
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239 | |
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240 | Returns an array of points inside and an array of points outside the polygon |
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241 | """ |
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242 | |
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243 | #if verbose: print 'Checking input to outside_polygon' |
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244 | try: |
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245 | points = ensure_numeric(points, Float) |
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246 | except NameError, e: |
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247 | raise NameError, e |
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248 | except: |
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249 | msg = 'Points could not be converted to Numeric array' |
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250 | raise msg |
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251 | |
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252 | try: |
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253 | polygon = ensure_numeric(polygon, Float) |
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254 | except NameError, e: |
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255 | raise NameError, e |
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256 | except: |
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257 | msg = 'Polygon could not be converted to Numeric array' |
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258 | raise msg |
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259 | |
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260 | if len(points.shape) == 1: |
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261 | # Only one point was passed in. Convert to array of points |
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262 | points = reshape(points, (1,2)) |
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263 | |
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264 | |
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265 | indices, count = separate_points_by_polygon(points, polygon, |
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266 | closed=closed, |
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267 | verbose=verbose) |
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268 | |
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269 | # Returns indices of points inside and indices of points outside |
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270 | # the polygon |
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271 | |
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272 | if count == len(indices): |
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273 | # No points are outside |
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274 | return indices[:count],[] |
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275 | else: |
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276 | return indices[:count], indices[count:][::-1] #return reversed |
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277 | |
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278 | |
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279 | def separate_points_by_polygon(points, polygon, |
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280 | closed = True, verbose = False): |
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281 | """Determine whether points are inside or outside a polygon |
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282 | |
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283 | Input: |
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284 | points - Tuple of (x, y) coordinates, or list of tuples |
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285 | polygon - list of vertices of polygon |
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286 | closed - (optional) determine whether points on boundary should be |
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287 | regarded as belonging to the polygon (closed = True) |
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288 | or not (closed = False) |
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289 | |
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290 | Outputs: |
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291 | indices: array of same length as points with indices of points falling |
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292 | inside the polygon listed from the beginning and indices of points |
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293 | falling outside listed from the end. |
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294 | |
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295 | count: count of points falling inside the polygon |
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296 | |
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297 | The indices of points inside are obtained as indices[:count] |
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298 | The indices of points outside are obtained as indices[count:] |
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299 | |
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300 | |
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301 | Examples: |
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302 | U = [[0,0], [1,0], [1,1], [0,1]] #Unit square |
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303 | |
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304 | separate_points_by_polygon( [[0.5, 0.5], [1, -0.5], [0.3, 0.2]], U) |
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305 | will return the indices [0, 2, 1] and count == 2 as only the first |
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306 | and the last point are inside the unit square |
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307 | |
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308 | Remarks: |
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309 | The vertices may be listed clockwise or counterclockwise and |
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310 | the first point may optionally be repeated. |
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311 | Polygons do not need to be convex. |
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312 | Polygons can have holes in them and points inside a hole is |
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313 | regarded as being outside the polygon. |
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314 | |
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315 | Algorithm is based on work by Darel Finley, |
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316 | http://www.alienryderflex.com/polygon/ |
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317 | |
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318 | Uses underlying C-implementation in polygon_ext.c |
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319 | """ |
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320 | |
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321 | |
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322 | #if verbose: print 'Checking input to separate_points_by_polygon' |
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323 | |
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324 | |
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325 | #Input checks |
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326 | |
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327 | assert isinstance(closed, bool), 'Keyword argument "closed" must be boolean' |
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328 | assert isinstance(verbose, bool), 'Keyword argument "verbose" must be boolean' |
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329 | |
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330 | |
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331 | try: |
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332 | points = ensure_numeric(points, Float) |
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333 | except NameError, e: |
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334 | raise NameError, e |
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335 | except: |
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336 | msg = 'Points could not be converted to Numeric array' |
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337 | raise msg |
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338 | |
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339 | #if verbose: print 'Checking input to separate_points_by_polygon 2' |
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340 | try: |
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341 | polygon = ensure_numeric(polygon, Float) |
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342 | except NameError, e: |
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343 | raise NameError, e |
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344 | except: |
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345 | msg = 'Polygon could not be converted to Numeric array' |
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346 | raise msg |
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347 | |
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348 | #if verbose: print 'check' |
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349 | |
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350 | assert len(polygon.shape) == 2,\ |
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351 | 'Polygon array must be a 2d array of vertices' |
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352 | |
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353 | assert polygon.shape[1] == 2,\ |
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354 | 'Polygon array must have two columns' |
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355 | |
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356 | assert len(points.shape) == 2,\ |
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357 | 'Points array must be a 2d array' |
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358 | |
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359 | assert points.shape[1] == 2,\ |
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360 | 'Points array must have two columns' |
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361 | |
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362 | N = polygon.shape[0] #Number of vertices in polygon |
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363 | M = points.shape[0] #Number of points |
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364 | |
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365 | |
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366 | indices = zeros( M, Int ) |
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367 | |
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368 | count = _separate_points_by_polygon(points, polygon, indices, |
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369 | int(closed), int(verbose)) |
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370 | |
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371 | if verbose: print 'Found %d points (out of %d) inside polygon'\ |
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372 | %(count, M) |
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373 | return indices, count |
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374 | |
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375 | |
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376 | def polygon_area(polygon): |
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377 | """ Determin area of arbitrary polygon |
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378 | Reference |
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379 | http://mathworld.wolfram.com/PolygonArea.html |
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380 | """ |
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381 | |
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382 | n = len(polygon) |
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383 | poly_area = 0.0 |
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384 | |
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385 | for i in range(n): |
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386 | pti = polygon[i] |
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387 | if i == n-1: |
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388 | pt1 = polygon[0] |
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389 | else: |
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390 | pt1 = polygon[i+1] |
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391 | xi = pti[0] |
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392 | yi1 = pt1[1] |
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393 | xi1 = pt1[0] |
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394 | yi = pti[1] |
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395 | poly_area += xi*yi1 - xi1*yi |
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396 | |
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397 | return abs(poly_area/2) |
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398 | |
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399 | def plot_polygons(polygons_points, style=None, |
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400 | figname=None, label=None, verbose=False): |
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401 | |
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402 | """ Take list of polygons and plot. |
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403 | |
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404 | Inputs: |
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405 | |
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406 | polygons - list of polygons |
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407 | |
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408 | style - style list corresponding to each polygon |
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409 | - for a polygon, use 'line' |
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410 | - for points falling outside a polygon, use 'outside' |
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411 | |
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412 | figname - name to save figure to |
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413 | |
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414 | label - title for plot |
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415 | |
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416 | Outputs: |
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417 | |
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418 | - list of min and max of x and y coordinates |
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419 | - plot of polygons |
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420 | """ |
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421 | |
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422 | from pylab import ion, hold, plot, axis, figure, legend, savefig, xlabel, ylabel, title, close, title |
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423 | |
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424 | assert type(polygons_points) == list,\ |
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425 | 'input must be a list of polygons and/or points' |
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426 | |
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427 | ion() |
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428 | hold(True) |
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429 | |
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430 | minx = 1e10 |
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431 | maxx = 0.0 |
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432 | miny = 1e10 |
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433 | maxy = 0.0 |
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434 | |
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435 | if label is None: label = '' |
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436 | |
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437 | n = len(polygons_points) |
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438 | colour = [] |
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439 | if style is None: |
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440 | style_type = 'line' |
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441 | style = [] |
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442 | for i in range(n): |
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443 | style.append(style_type) |
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444 | colour.append('b-') |
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445 | else: |
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446 | for s in style: |
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447 | if s == 'line': colour.append('b-') |
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448 | if s == 'outside': colour.append('r.') |
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449 | if s <> 'line': |
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450 | if s <> 'outside': |
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451 | colour.append('g.') |
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452 | |
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453 | for i, item in enumerate(polygons_points): |
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454 | x, y = poly_xy(item) |
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455 | if min(x) < minx: minx = min(x) |
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456 | if max(x) > maxx: maxx = max(x) |
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457 | if min(y) < miny: miny = min(y) |
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458 | if max(y) > maxy: maxy = max(y) |
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459 | plot(x,y,colour[i]) |
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460 | xlabel('x') |
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461 | ylabel('y') |
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462 | title(label) |
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463 | |
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464 | #raw_input('wait 1') |
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465 | #FIXME(Ole): This makes for some strange scalings sometimes. |
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466 | #if minx <> 0: |
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467 | # axis([minx*0.9,maxx*1.1,miny*0.9,maxy*1.1]) |
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468 | #else: |
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469 | # if miny == 0: |
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470 | # axis([-maxx*.01,maxx*1.1,-maxy*0.01,maxy*1.1]) |
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471 | # else: |
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472 | # axis([-maxx*.01,maxx*1.1,miny*0.9,maxy*1.1]) |
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473 | |
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474 | if figname is not None: |
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475 | savefig(figname) |
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476 | else: |
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477 | savefig('test_image') |
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478 | |
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479 | close('all') |
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480 | |
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481 | vec = [minx,maxx,miny,maxy] |
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482 | |
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483 | return vec |
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484 | |
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485 | def poly_xy(polygon, verbose=False): |
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486 | """ this is used within plot_polygons so need to duplicate |
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487 | the first point so can have closed polygon in plot |
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488 | """ |
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489 | |
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490 | #if verbose: print 'Checking input to poly_xy' |
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491 | |
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492 | try: |
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493 | polygon = ensure_numeric(polygon, Float) |
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494 | except NameError, e: |
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495 | raise NameError, e |
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496 | except: |
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497 | msg = 'Polygon %s could not be converted to Numeric array' %(str(polygon)) |
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498 | raise msg |
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499 | |
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500 | x = polygon[:,0] |
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501 | y = polygon[:,1] |
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502 | x = concatenate((x, [polygon[0,0]]), axis = 0) |
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503 | y = concatenate((y, [polygon[0,1]]), axis = 0) |
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504 | |
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505 | return x, y |
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506 | |
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507 | # x = [] |
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508 | # y = [] |
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509 | # n = len(poly) |
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510 | # firstpt = poly[0] |
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511 | # for i in range(n): |
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512 | # thispt = poly[i] |
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513 | # x.append(thispt[0]) |
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514 | # y.append(thispt[1]) |
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515 | |
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516 | # x.append(firstpt[0]) |
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517 | # y.append(firstpt[1]) |
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518 | |
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519 | # return x, y |
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520 | |
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521 | class Polygon_function: |
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522 | """Create callable object f: x,y -> z, where a,y,z are vectors and |
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523 | where f will return different values depending on whether x,y belongs |
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524 | to specified polygons. |
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525 | |
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526 | To instantiate: |
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527 | |
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528 | Polygon_function(polygons) |
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529 | |
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530 | where polygons is a list of tuples of the form |
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531 | |
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532 | [ (P0, v0), (P1, v1), ...] |
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533 | |
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534 | with Pi being lists of vertices defining polygons and vi either |
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535 | constants or functions of x,y to be applied to points with the polygon. |
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536 | |
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537 | The function takes an optional argument, default which is the value |
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538 | (or function) to used for points not belonging to any polygon. |
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539 | For example: |
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540 | |
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541 | Polygon_function(polygons, default = 0.03) |
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542 | |
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543 | If omitted the default value will be 0.0 |
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544 | |
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545 | Note: If two polygons overlap, the one last in the list takes precedence |
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546 | |
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547 | Coordinates specified in the call are assumed to be relative to the |
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548 | origin (georeference) e.g. used by domain. |
---|
549 | By specifying the optional argument georeference, |
---|
550 | all points are made relative. |
---|
551 | |
---|
552 | FIXME: This should really work with geo_spatial point sets. |
---|
553 | """ |
---|
554 | |
---|
555 | def __init__(self, regions, default=0.0, geo_reference=None): |
---|
556 | |
---|
557 | try: |
---|
558 | len(regions) |
---|
559 | except: |
---|
560 | msg = 'Polygon_function takes a list of pairs (polygon, value).' |
---|
561 | msg += 'Got %s' %polygons |
---|
562 | raise msg |
---|
563 | |
---|
564 | |
---|
565 | T = regions[0] |
---|
566 | try: |
---|
567 | a = len(T) |
---|
568 | except: |
---|
569 | msg = 'Polygon_function takes a list of pairs (polygon, value).' |
---|
570 | msg += 'Got %s' %polygons |
---|
571 | raise msg |
---|
572 | |
---|
573 | assert a == 2, 'Must have two component each: %s' %T |
---|
574 | |
---|
575 | |
---|
576 | if geo_reference is None: |
---|
577 | from anuga.coordinate_transforms.geo_reference import Geo_reference |
---|
578 | geo_reference = Geo_reference() |
---|
579 | |
---|
580 | |
---|
581 | self.default = default |
---|
582 | |
---|
583 | # Make points in polygons relative to geo_reference |
---|
584 | self.regions = [] |
---|
585 | for polygon, value in regions: |
---|
586 | P = geo_reference.change_points_geo_ref(polygon) |
---|
587 | self.regions.append( (P, value) ) |
---|
588 | |
---|
589 | |
---|
590 | |
---|
591 | |
---|
592 | def __call__(self, x, y): |
---|
593 | x = array(x).astype(Float) |
---|
594 | y = array(y).astype(Float) |
---|
595 | |
---|
596 | N = len(x) |
---|
597 | assert len(y) == N |
---|
598 | |
---|
599 | points = concatenate( (reshape(x, (N, 1)), |
---|
600 | reshape(y, (N, 1))), axis=1 ) |
---|
601 | |
---|
602 | if callable(self.default): |
---|
603 | z = self.default(x,y) |
---|
604 | else: |
---|
605 | z = ones(N, Float) * self.default |
---|
606 | |
---|
607 | for polygon, value in self.regions: |
---|
608 | indices = inside_polygon(points, polygon) |
---|
609 | |
---|
610 | # FIXME: This needs to be vectorised |
---|
611 | if callable(value): |
---|
612 | for i in indices: |
---|
613 | xx = array([x[i]]) |
---|
614 | yy = array([y[i]]) |
---|
615 | z[i] = value(xx, yy)[0] |
---|
616 | else: |
---|
617 | for i in indices: |
---|
618 | z[i] = value |
---|
619 | |
---|
620 | return z |
---|
621 | |
---|
622 | |
---|
623 | def read_polygon(filename, split=','): |
---|
624 | """Read points assumed to form a polygon. |
---|
625 | There must be exactly two numbers in each line separated by a comma. |
---|
626 | No header. |
---|
627 | """ |
---|
628 | |
---|
629 | #Get polygon |
---|
630 | fid = open(filename) |
---|
631 | lines = fid.readlines() |
---|
632 | fid.close() |
---|
633 | polygon = [] |
---|
634 | for line in lines: |
---|
635 | fields = line.split(split) |
---|
636 | polygon.append( [float(fields[0]), float(fields[1])] ) |
---|
637 | |
---|
638 | return polygon |
---|
639 | |
---|
640 | |
---|
641 | def write_polygon(polygon, filename=None): |
---|
642 | """Write polygon to csv file. |
---|
643 | There will be exactly two numbers, easting and northing, |
---|
644 | in each line separated by a comma. |
---|
645 | |
---|
646 | No header. |
---|
647 | """ |
---|
648 | |
---|
649 | fid = open(filename, 'w') |
---|
650 | for point in polygon: |
---|
651 | fid.write('%f, %f\n' %point) |
---|
652 | fid.close() |
---|
653 | |
---|
654 | |
---|
655 | def populate_polygon(polygon, number_of_points, seed=None, exclude=None): |
---|
656 | """Populate given polygon with uniformly distributed points. |
---|
657 | |
---|
658 | Input: |
---|
659 | polygon - list of vertices of polygon |
---|
660 | number_of_points - (optional) number of points |
---|
661 | seed - seed for random number generator (default=None) |
---|
662 | exclude - list of polygons (inside main polygon) from where points should be excluded |
---|
663 | |
---|
664 | Output: |
---|
665 | points - list of points inside polygon |
---|
666 | |
---|
667 | Examples: |
---|
668 | populate_polygon( [[0,0], [1,0], [1,1], [0,1]], 5 ) |
---|
669 | will return five randomly selected points inside the unit square |
---|
670 | """ |
---|
671 | |
---|
672 | from random import uniform, seed as seed_function |
---|
673 | |
---|
674 | seed_function(seed) |
---|
675 | |
---|
676 | points = [] |
---|
677 | |
---|
678 | # Find outer extent of polygon |
---|
679 | max_x = min_x = polygon[0][0] |
---|
680 | max_y = min_y = polygon[0][1] |
---|
681 | for point in polygon[1:]: |
---|
682 | x = point[0] |
---|
683 | if x > max_x: max_x = x |
---|
684 | if x < min_x: min_x = x |
---|
685 | y = point[1] |
---|
686 | if y > max_y: max_y = y |
---|
687 | if y < min_y: min_y = y |
---|
688 | |
---|
689 | |
---|
690 | while len(points) < number_of_points: |
---|
691 | x = uniform(min_x, max_x) |
---|
692 | y = uniform(min_y, max_y) |
---|
693 | |
---|
694 | append = False |
---|
695 | if is_inside_polygon([x,y], polygon): |
---|
696 | |
---|
697 | append = True |
---|
698 | |
---|
699 | #Check exclusions |
---|
700 | if exclude is not None: |
---|
701 | for ex_poly in exclude: |
---|
702 | if is_inside_polygon([x,y], ex_poly): |
---|
703 | append = False |
---|
704 | |
---|
705 | |
---|
706 | if append is True: |
---|
707 | points.append([x,y]) |
---|
708 | |
---|
709 | return points |
---|
710 | |
---|
711 | |
---|
712 | def point_in_polygon(polygon, delta=1e-8): |
---|
713 | """Return a point inside a given polygon which will be close to the |
---|
714 | polygon edge. |
---|
715 | |
---|
716 | Input: |
---|
717 | polygon - list of vertices of polygon |
---|
718 | delta - the square root of 2 * delta is the maximum distance from the |
---|
719 | polygon points and the returned point. |
---|
720 | Output: |
---|
721 | points - a point inside polygon |
---|
722 | |
---|
723 | searches in all diagonals and up and down (not left and right) |
---|
724 | """ |
---|
725 | import exceptions |
---|
726 | class Found(exceptions.Exception): pass |
---|
727 | |
---|
728 | point_in = False |
---|
729 | while not point_in: |
---|
730 | try: |
---|
731 | for poly_point in polygon: #[1:]: |
---|
732 | for x_mult in range (-1,2): |
---|
733 | for y_mult in range (-1,2): |
---|
734 | x = poly_point[0] |
---|
735 | y = poly_point[1] |
---|
736 | if x == 0: |
---|
737 | x_delta = x_mult*delta |
---|
738 | else: |
---|
739 | x_delta = x+x_mult*x*delta |
---|
740 | |
---|
741 | if y == 0: |
---|
742 | y_delta = y_mult*delta |
---|
743 | else: |
---|
744 | y_delta = y+y_mult*y*delta |
---|
745 | |
---|
746 | point = [x_delta, y_delta] |
---|
747 | #print "point",point |
---|
748 | if is_inside_polygon(point, polygon, closed=False): |
---|
749 | raise Found |
---|
750 | except Found: |
---|
751 | point_in = True |
---|
752 | else: |
---|
753 | delta = delta*0.1 |
---|
754 | return point |
---|
755 | |
---|
756 | |
---|
757 | def number_mesh_triangles(interior_regions, bounding_poly, remainder_res): |
---|
758 | """Calculate the approximate number of triangles inside the |
---|
759 | bounding polygon and the other interior regions |
---|
760 | |
---|
761 | Polygon areas are converted to square Kms |
---|
762 | |
---|
763 | FIXME: Add tests for this function |
---|
764 | """ |
---|
765 | |
---|
766 | from anuga.utilities.polygon import polygon_area |
---|
767 | |
---|
768 | |
---|
769 | # TO DO check if any of the regions fall inside one another |
---|
770 | |
---|
771 | print '----------------------------------------------------------------------------' |
---|
772 | print 'Polygon Max triangle area (m^2) Total area (km^2) Estimated #triangles' |
---|
773 | print '----------------------------------------------------------------------------' |
---|
774 | |
---|
775 | no_triangles = 0.0 |
---|
776 | area = polygon_area(bounding_poly) |
---|
777 | |
---|
778 | for poly, resolution in interior_regions: |
---|
779 | this_area = polygon_area(poly) |
---|
780 | this_triangles = this_area/resolution |
---|
781 | no_triangles += this_triangles |
---|
782 | area -= this_area |
---|
783 | |
---|
784 | print 'Interior ', |
---|
785 | print ('%.0f' %resolution).ljust(25), |
---|
786 | print ('%.2f' %(this_area/1000000)).ljust(19), |
---|
787 | print '%d' %(this_triangles) |
---|
788 | |
---|
789 | bound_triangles = area/remainder_res |
---|
790 | no_triangles += bound_triangles |
---|
791 | |
---|
792 | print 'Bounding ', |
---|
793 | print ('%.0f' %remainder_res).ljust(25), |
---|
794 | print ('%.2f' %(area/1000000)).ljust(19), |
---|
795 | print '%d' %(bound_triangles) |
---|
796 | |
---|
797 | total_number_of_triangles = no_triangles/0.7 |
---|
798 | |
---|
799 | print 'Estimated total number of triangles: %d' %total_number_of_triangles |
---|
800 | print 'Note: This is generally about 20% less than the final amount' |
---|
801 | |
---|
802 | return int(total_number_of_triangles) |
---|
803 | |
---|
804 | |
---|
805 | def decimate_polygon(polygon, factor=10): |
---|
806 | """Reduce number of points in polygon by the specified |
---|
807 | factor (default=10, hence the name of the function) such that |
---|
808 | the extrema in both axes are preserved. |
---|
809 | |
---|
810 | Return reduced polygon |
---|
811 | """ |
---|
812 | |
---|
813 | # FIXME(Ole): This doesn't work at present, |
---|
814 | # but it isn't critical either |
---|
815 | |
---|
816 | # Find outer extent of polygon |
---|
817 | num_polygon = ensure_numeric(polygon) |
---|
818 | max_x = max(num_polygon[:,0]) |
---|
819 | max_y = max(num_polygon[:,1]) |
---|
820 | min_x = min(num_polygon[:,0]) |
---|
821 | min_y = min(num_polygon[:,1]) |
---|
822 | |
---|
823 | # Keep only some points making sure extrema are kept |
---|
824 | reduced_polygon = [] |
---|
825 | for i, point in enumerate(polygon): |
---|
826 | x = point[0] |
---|
827 | y = point[1] |
---|
828 | if x in [min_x, max_x] and y in [min_y, max_y]: |
---|
829 | # Keep |
---|
830 | reduced_polygon.append(point) |
---|
831 | else: |
---|
832 | if len(reduced_polygon)*factor < i: |
---|
833 | reduced_polygon.append(point) |
---|
834 | |
---|
835 | return reduced_polygon |
---|
836 | |
---|
837 | ############################################## |
---|
838 | #Initialise module |
---|
839 | |
---|
840 | from anuga.utilities.compile import can_use_C_extension |
---|
841 | if can_use_C_extension('polygon_ext.c'): |
---|
842 | # Underlying C implementations can be accessed |
---|
843 | from polygon_ext import _point_on_line |
---|
844 | from polygon_ext import _separate_points_by_polygon |
---|
845 | |
---|
846 | else: |
---|
847 | msg = 'C implementations could not be accessed by %s.\n ' %__file__ |
---|
848 | msg += 'Make sure compile_all.py has been run as described in ' |
---|
849 | msg += 'the ANUGA installation guide.' |
---|
850 | raise Exception, msg |
---|
851 | |
---|
852 | |
---|
853 | if __name__ == "__main__": |
---|
854 | pass |
---|