source: branches/numpy/anuga/abstract_2d_finite_volumes/generic_boundary_conditions.py @ 6463

"""boundary.py - Classes for implementing boundary conditions
"""

from warnings import warn

from anuga.utilities.numerical_tools import NAN    
from anuga.fit_interpolate.interpolate import Modeltime_too_late
from anuga.fit_interpolate.interpolate import Modeltime_too_early

import numpy as num


class Boundary:
    """Base class for boundary conditions.
       Specific boundary conditions must provide values for
       the conserved_quantities

       A boundary object has one neighbour; the one it
       serves.
    """

    def __init__(self):
        pass

    def evaluate(self, vol_id=None, edge_id=None):
        msg = 'Generic class Boundary must be subclassed'
        raise Exception, msg


class Transmissive_boundary(Boundary):
    """Transmissive boundary returns same conserved quantities as
    those present in its neighbour volume.

    Underlying domain must be specified when boundary is instantiated
    """

    def __init__(self, domain = None):
        Boundary.__init__(self)

        if domain is None:
            msg = 'Domain must be specified for transmissive boundary'
            raise Exception, msg

        self.domain = domain

    def __repr__(self):
        return 'Transmissive_boundary(%s)' %self.domain

    def evaluate(self, vol_id, edge_id):
        """Transmissive boundaries return the edge values
        of the volume they serve.
        """

        q = self.domain.get_conserved_quantities(vol_id, edge = edge_id)
        return q


class Dirichlet_boundary(Boundary):
    """Dirichlet boundary returns constant values for the
    conserved quantities
    """


    def __init__(self, conserved_quantities=None):
        Boundary.__init__(self)

        if conserved_quantities is None:
            msg = 'Must specify one value for each conserved quantity'
            raise Exception, msg

        self.conserved_quantities=num.array(conserved_quantities, num.float)

    def __repr__(self):
        return 'Dirichlet boundary (%s)' %self.conserved_quantities

    def evaluate(self, vol_id=None, edge_id=None):
        return self.conserved_quantities



class Time_boundary(Boundary):
    """Time dependent boundary returns values for the
    conserved quantities as a function of time.
    Must specify domain to get access to model time and a function f(t)
    which must return conserved quantities as a function time
    """

    # FIXME (Ole): We should rename f to function to be consistent with
    # Transmissive_Momentum_Set_Stage_Boundary (cf posting by rrraman)
    def __init__(self, domain = None, f = None):
        Boundary.__init__(self)

        try:
            q = f(0.0)
        except Exception, e:
            msg = 'Function for time boundary could not be executed:\n%s' %e
            raise msg


        try:
            q = num.array(q, num.float)
        except:
            msg = 'Return value from time boundary function could '
            msg += 'not be converted into a numeric array of floats.\n'
            msg += 'Specified function should return either list or array.\n'
            msg += 'I got %s' %str(q)
            raise msg

        msg = 'ERROR: Time boundary function must return a 1d list or array '
        assert len(q.shape) == 1, msg

        d = len(domain.conserved_quantities)
        msg = 'Return value for f must be a list or an array of length %d' %d
        assert len(q) == d, msg

        self.f = f
        self.domain = domain

    def __repr__(self):
        return 'Time boundary'

    def evaluate(self, vol_id=None, edge_id=None):
        # FIXME (Ole): I think this should be get_time(), see ticket:306
        return self.f(self.domain.time)



class File_boundary(Boundary):
    """The File_boundary reads values for the conserved
    quantities from an sww NetCDF file, and returns interpolated values
    at the midpoints of each associated boundary segment.
    Time dependency is interpolated linearly.

    Assumes that file contains a time series and possibly
    also spatial info. See docstring for File_function in util.py
    for details about admissible file formats

    File boundary must read and interpolate from *smoothed* version
    as stored in sww and cannot work with the discontinuos triangles.

    Example:
    Bf = File_boundary('source_file.sww', domain)


    Note that the resulting solution history is not exactly the same as if
    the models were coupled as there is no feedback into the source model.
    
    Optional keyword argument default_boundary must be either None or 
    an instance of class descending from class Boundary.
    This will be used in case model time exceeds that available in the 
    underlying data.
       
    """

    # FIXME (Ole): I kind of like the name Spatio_Temporal_boundary for this
    # rather than File_boundary

    def __init__(self, filename, domain, 
                 time_thinning=1, 
                 time_limit=None,
                 boundary_polygon=None,    
                 default_boundary=None,
                 use_cache=False, 
                 verbose=False): 

        import time
        from anuga.config import time_format
        from anuga.abstract_2d_finite_volumes.util import file_function

        Boundary.__init__(self)

        # Get x,y vertex coordinates for all triangles
        V = domain.vertex_coordinates

        # Compute midpoint coordinates for all boundary elements
        # Only a subset may be invoked when boundary is evaluated but
        # we don't know which ones at this stage since this object can
        # be attached to
        # any tagged boundary later on.

        if verbose: print 'Find midpoint coordinates of entire boundary'
        self.midpoint_coordinates = num.zeros((len(domain.boundary), 2), num.float)
        boundary_keys = domain.boundary.keys()

        xllcorner = domain.geo_reference.get_xllcorner()
        yllcorner = domain.geo_reference.get_yllcorner()        
        

        # Make ordering unique #FIXME: should this happen in domain.py?
        boundary_keys.sort()

        # Record ordering #FIXME: should this also happen in domain.py?
        self.boundary_indices = {}
        for i, (vol_id, edge_id) in enumerate(boundary_keys):

            base_index = 3*vol_id
            x0, y0 = V[base_index, :]
            x1, y1 = V[base_index+1, :]
            x2, y2 = V[base_index+2, :]
            
            # Compute midpoints
            if edge_id == 0: m = num.array([(x1 + x2)/2, (y1 + y2)/2], num.float)
            if edge_id == 1: m = num.array([(x0 + x2)/2, (y0 + y2)/2], num.float)
            if edge_id == 2: m = num.array([(x1 + x0)/2, (y1 + y0)/2], num.float)

            # Convert to absolute UTM coordinates
            m[0] += xllcorner
            m[1] += yllcorner
            
            # Register point and index
            self.midpoint_coordinates[i,:] = m

            # Register index of this boundary edge for use with evaluate
            self.boundary_indices[(vol_id, edge_id)] = i

        if verbose: print 'Initialise file_function'
        self.F = file_function(filename,
                               domain,
                               quantities=domain.conserved_quantities,
                               interpolation_points=self.midpoint_coordinates,
                               time_thinning=time_thinning,
                               time_limit=time_limit,
                               use_cache=use_cache, 
                               verbose=verbose,
                               boundary_polygon=boundary_polygon)
                             
        # Check and store default_boundary
        msg = 'Keyword argument default_boundary must be either None '
        msg += 'or a boundary object.\n I got %s' %(str(default_boundary))
        assert default_boundary is None or\
            isinstance(default_boundary, Boundary), msg
        self.default_boundary = default_boundary
        self.default_boundary_invoked = False    # Flag

        # Store pointer to domain and verbosity
        self.domain = domain
        self.verbose = verbose


        # Here we'll flag indices outside the mesh as a warning
        # as suggested by Joaquim Luis in sourceforge posting
        # November 2007
        # We won't make it an error as it is conceivable that
        # only part of mesh boundary is actually used with a given
        # file boundary sww file. 
        if hasattr(self.F, 'indices_outside_mesh') and\
               len(self.F.indices_outside_mesh) > 0:
            msg = 'WARNING: File_boundary has points outside the mesh '
            msg += 'given in %s. ' %filename
            msg += 'See warning message issued by Interpolation_function '
            msg += 'for details (should appear above somewhere if '
            msg += 'verbose is True).\n'
            msg += 'This is perfectly OK as long as the points that are '
            msg += 'outside aren\'t used on the actual boundary segment.'
            if verbose is True:            
                print msg
            #raise Exception(msg)

        # Test that file function can be called
        q = self.F(0, point_id=0)
        d = len(domain.conserved_quantities)
        msg = 'Values specified in file %s must be ' %filename
        msg += ' a list or an array of length %d' %d
        assert len(q) == d, msg


    def __repr__(self):
        return 'File boundary'


    def evaluate(self, vol_id=None, edge_id=None):
        """Return linearly interpolated values based on domain.time
        at midpoint of segment defined by vol_id and edge_id.
        """

        # FIXME (Ole): I think this should be get_time(), see ticket:306
        t = self.domain.time
        
        if vol_id is not None and edge_id is not None:
            i = self.boundary_indices[ vol_id, edge_id ]
            
            try:
                res = self.F(t, point_id=i)
            except Modeltime_too_early, e:
                raise Modeltime_too_early, e
            except Modeltime_too_late, e:
                if self.default_boundary is None:
                    raise Exception, e # Reraise exception
                else:
                    # Pass control to default boundary
                    res = self.default_boundary.evaluate(vol_id, edge_id)
                    
                    # Ensure that result cannot be manipulated
                    # This is a real danger in case the 
                    # default_boundary is a Dirichlet type 
                    # for instance. 
                    res = res.copy() 
                    
                    if self.default_boundary_invoked is False:
                        # Issue warning the first time
                        msg = '%s' %str(e)
                        msg += 'Instead I will use the default boundary: %s\n'\
                            %str(self.default_boundary) 
                        msg += 'Note: Further warnings will be supressed'
                        warn(msg)
                   
                        # FIXME (Ole): Replace this crude flag with
                        # Python's ability to print warnings only once.
                        # See http://docs.python.org/lib/warning-filter.html
                        self.default_boundary_invoked = True
            
            if num.any(res == NAN):
                x,y=self.midpoint_coordinates[i,:]
                msg = 'NAN value found in file_boundary at '
                msg += 'point id #%d: (%.2f, %.2f).\n' %(i, x, y)

                if hasattr(self.F, 'indices_outside_mesh') and\
                       len(self.F.indices_outside_mesh) > 0:
                    # Check if NAN point is due it being outside
                    # boundary defined in sww file.

                    if i in self.F.indices_outside_mesh:
                        msg += 'This point refers to one outside the '
                        msg += 'mesh defined by the file %s.\n'\
                               %self.F.filename
                        msg += 'Make sure that the file covers '
                        msg += 'the boundary segment it is assigned to '
                        msg += 'in set_boundary.'
                    else:
                        msg += 'This point is inside the mesh defined '
                        msg += 'the file %s.\n' %self.F.filename
                        msg += 'Check this file for NANs.'
                raise Exception, msg
            
            return res 
        else:
            msg = 'Boundary call without point_id not implemented.\n'
            msg += 'vol_id=%s, edge_id=%s' %(str(vol_id), str(edge_id))
            raise Exception, msg