Source code for safe.gis.interpolation

# coding=utf-8
""" **Commonalities used in both 1d and 2d interpolation**

This module provides commonalities shared between interpolation1d and
interpolation2d. This includes input data validation methods.

import numpy

from safe.common.exceptions import BoundsError, InaSAFEError

[docs]def validate_mode(mode): """Validate that the mode is an allowable value. :param mode: Determines the interpolation order. Options are: * 'constant' - piecewise constant nearest neighbour interpolation * 'linear' - bilinear interpolation using the two nearest \ neighbours (default) :type mode: str :raises: InaSAFEError """ msg = ( 'Only mode "linear" and "constant" are implemented. I got "%s"' % mode) if mode not in ['linear', 'constant']: raise InaSAFEError(msg)
[docs]def validate_coordinate_vector(coordinates, coordinate_name): """Validate that the coordinates vector are valid :param coordinates: The coordinates vector :type coordinates: numpy.ndarray :param coordinate_name: The user recognizable name of the coordinates. :type coordinate_name: str :raise: Exception, InaSAFEError :returns: Coordinates cast as a numpy arry """ try: coordinates = numpy.array(coordinates) except Exception, e: msg = ( 'Input vector %s could not be converted to numpy array: ' '%s' % (coordinate_name, str(e))) raise Exception(msg) if not min(coordinates) == coordinates[0]: msg = ( 'Input vector %s must be monotoneously increasing. ' 'I got min(%s) == %.15f, but coordinates[0] == %.15f' % ( coordinate_name, coordinate_name, min(coordinates), coordinates[0])) raise InaSAFEError(msg) if not max(coordinates) == coordinates[-1]: msg = ( 'Input vector coordinates must be monotoneously increasing. I got ' 'max(coordinates) == %.15f, but coordinates[-1] == %.15f' % ( max(coordinates), coordinates[-1])) raise InaSAFEError(msg) return coordinates
[docs]def validate_inputs( x=None, y=None, z=None, points=None, bounds_error=None): """Check inputs for interpolate1d and interpolate2d functions :param x: 1D array of x-coordinates on which to interpolate :type x: numpy.ndarray :param y: 1D array of y-coordinates on which to interpolate :type z: numpy.ndarray :param z: array of values for each x :type z: numpy.ndarray :param points: 1D array of coordinates where interpolated values are sought :type points: numpy.ndarray :param bounds_error: Flag to indicate whether an exception will be raised when interpolated values are requested outside the domain of the input data. If False, nan is returned for those values. :type bounds_error: bool :returns: x, z and points :raises: RuntimeError, Exception """ x = validate_coordinate_vector(x, 'x') if y is None: dimensions = 1 else: dimensions = 2 y = validate_coordinate_vector(y, 'y') try: z = numpy.array(z) except Exception, e: msg = ( 'Input vector z could not be converted to a numpy array: ' '%s' % str(e)) raise Exception(msg) if len(z.shape) != dimensions: msg = 'z must be a %iD numpy array got a: %dD' % ( dimensions, len(z.shape)) raise Exception(msg) Nx = len(x) points = numpy.array(points) if not len(points.shape) == dimensions: msg = 'Interpolation points must be a %id array' % dimensions raise RuntimeError(msg) if dimensions == 1: (m,) = z.shape if not Nx == m: msg = ( 'Input array z must have same length as x (%i).' 'However, Z has length %i.' % (Nx, m)) raise RuntimeError(msg) # Get interpolation points xi = points[:] else: (m, n) = z.shape Ny = len(y) if not (Nx == m and Ny == n): msg = ( 'Input array Z must have dimensions %i x %i corresponding to ' 'the lengths of the input coordinates x and y. However, ' 'Z has dimensions %i x %i.' % (Nx, Ny, m, n)) raise InaSAFEError(msg) # Get interpolation points points = numpy.array(points) xi = points[:, 0] eta = points[:, 1] if bounds_error: xi0 = min(xi) xi1 = max(xi) if xi0 < x[0]: msg = ( 'Interpolation point xi=%f was less than the smallest ' 'value in domain (x=%f) and bounds_error was requested.' % (xi0, x[0])) raise BoundsError(msg) if xi1 > x[-1]: msg = ( 'Interpolation point xi=%f was greater than the largest ' 'value in domain (x=%f) and bounds_error was requested.' % (xi1, x[-1])) raise BoundsError(msg) if dimensions == 2: # noinspection PyUnboundLocalVariable eta0 = min(eta) eta1 = max(eta) if eta0 < y[0]: msg = ( 'Interpolation point eta=%f was less than the smallest ' 'value in domain (y=%f) and bounds_error was requested.' % (eta0, y[0])) raise BoundsError(msg) if eta1 > y[-1]: msg = ( 'Interpolation point eta=%f was greater than the largest ' 'value in domain (y=%f) and bounds_error was requested.' % (eta1, y[-1])) raise BoundsError(msg) # TODO this is problematic as pylint can't see how many args to expect back if dimensions == 1: return x, z, xi else: return x, y, z, xi, eta