Changeset 2912 for inundation/utilities

Timestamp:

May 18, 2006, 4:32:42 PM (18 years ago)

Author:

sexton

Message:

incorporate plot_polygon in polygon rather than pyvolution.util; also polygon_area functionality added

Location:

inundation/utilities

Files:

• polygon.py (modified) (1 diff)
• test_polygon.py (modified) (1 diff)

inundation/utilities/polygon.py

@@ -378 +378 @@
 
 
+def polygon_area(polygon):
+    """ Determin area of arbitrary polygon
+    Reference
+    http://mathworld.wolfram.com/PolygonArea.html
+    """
+    
+    n = len(polygon)
+    poly_area = 0.0
+
+    for i in range(n):
+        pti = polygon[i]
+        if i == n-1:
+            pt1 = polygon[0]
+        else:
+            pt1 = polygon[i+1]
+        xi = pti[0]
+        yi1 = pt1[1]
+        xi1 = pt1[0]
+        yi = pti[1]
+        poly_area += xi*yi1 - xi1*yi
+        
+    return abs(poly_area/2)
+
+def plot_polygons(polygons,
+                  figname,
+                  verbose = False):
+    
+    """ Take list of polygons and plot.
+
+    Inputs:
+
+    polygons         - list of polygons
+                        
+    figname          - name to save figure to
+
+    Outputs:
+
+    - list of min and max of x and y coordinates
+    - plot of polygons
+    """ 
+
+    from pylab import ion, hold, plot, axis, figure, legend, savefig, xlabel, ylabel, title, close
+
+    assert type(polygons) == list,\
+               'polygon must be a list'
+
+    ion()
+    hold(True)
+
+    minx = 1e10
+    maxx = 0.0
+    miny = 1e10
+    maxy = 0.0
+    for i in range(len(polygons)):
+        x, y = poly_xy(polygons[i])  
+        if min(x) < minx: minx = min(x)
+        if max(x) > maxx: maxx = max(x)
+        if min(y) < miny: miny = min(y)
+        if max(y) > maxy: maxy = max(y)
+        plot(x,y,'r-')
+        xlabel('x')
+        ylabel('y')
+
+    savefig(figname)
+
+    close('all')
+
+    vec = [minx,maxx,miny,maxy]
+
+    return vec
+
+def poly_xy(poly):
+    """ this is used within plot_polygons so need to duplicate
+        the first point so can have closed polygon in plot
+    """
+
+    assert type(poly[0]) == list,\
+               'polygon must be a list of points'
+    
+    x = []
+    y = []
+    n = len(poly)
+    firstpt = poly[0]
+    for i in range(n):
+        thispt = poly[i]
+        x.append(thispt[0])
+        y.append(thispt[1])
+
+    x.append(firstpt[0])
+    y.append(firstpt[1])
+    
+    return x, y
 
 class Polygon_function:

inundation/utilities/test_polygon.py

@@ -548 +548 @@
         assert len(res) == 2
         assert allclose(res, [0,1])
-        
+
+    def test_polygon_area(self):
+
+        #Simplest case: Polygon is the unit square
+        polygon = [[0,0], [1,0], [1,1], [0,1]]
+        assert polygon_area(polygon) == 1
+
+        #Simple case: Polygon is a rectangle
+        polygon = [[0,0], [1,0], [1,4], [0,4]]
+        assert polygon_area(polygon) == 4
+
+        #Simple case: Polygon is a unit triangle
+        polygon = [[0,0], [1,0], [0,1]]
+        assert polygon_area(polygon) == 0.5
+
+        #Simple case: Polygon is a diamond
+        polygon = [[0,0], [1,1], [2,0], [1, -1]]
+        assert polygon_area(polygon) == 2.0
+
+    def test_poly_xy(self):
+ 
+        #Simplest case: Polygon is the unit square
+        polygon = [[0,0], [1,0], [1,1], [0,1]]
+        x, y = poly_xy(polygon)
+        assert len(x) == len(polygon)+1
+        assert len(y) == len(polygon)+1
+        assert x[0] == 0
+        assert x[1] == 1
+        assert x[2] == 1
+        assert x[3] == 0
+        assert y[0] == 0
+        assert y[1] == 0
+        assert y[2] == 1
+        assert y[3] == 1
+
+        #Arbitrary polygon
+        polygon = [[1,5], [1,1], [100,10], [1,10], [3,6]]
+        x, y = poly_xy(polygon)
+        assert len(x) == len(polygon)+1
+        assert len(y) == len(polygon)+1
+        assert x[0] == 1
+        assert x[1] == 1
+        assert x[2] == 100
+        assert x[3] == 1
+        assert x[4] == 3
+        assert y[0] == 5
+        assert y[1] == 1
+        assert y[2] == 10
+        assert y[3] == 10
+        assert y[4] == 6
+
+    def test_plot_polygons(self):
+
+        import os
+        
+        #Simplest case: Polygon is the unit square
+        polygon1 = [[0,0], [1,0], [1,1], [0,1]]
+        polygon2 = [[1,1], [2,1], [3,2], [2,2]]
+        v = plot_polygons([polygon1, polygon2],'test1')
+        assert len(v) == 4
+        assert v[0] == 0
+        assert v[1] == 3
+        assert v[2] == 0
+        assert v[3] == 2
+
+        #Another case
+        polygon3 = [[1,5], [10,1], [100,10], [50,10], [3,6]]
+        v = plot_polygons([polygon2,polygon3],'test2')
+        assert len(v) == 4
+        assert v[0] == 1
+        assert v[1] == 100
+        assert v[2] == 1
+        assert v[3] == 10
+
+        os.remove('test1.png')
+        os.remove('test2.png')
+        
 #-------------------------------------------------------------
 if __name__ == "__main__":