Fixed database typo and removed unnecessary class identifier.

venv/Lib/site-packages/scipy/interpolate/ndgriddata.py

@@ -0,0 +1,227 @@
+"""
+Convenience interface to N-D interpolation
+
+.. versionadded:: 0.9
+
+"""
+import numpy as np
+from .interpnd import LinearNDInterpolator, NDInterpolatorBase, \
+     CloughTocher2DInterpolator, _ndim_coords_from_arrays
+from scipy.spatial import cKDTree
+
+__all__ = ['griddata', 'NearestNDInterpolator', 'LinearNDInterpolator',
+           'CloughTocher2DInterpolator']
+
+#------------------------------------------------------------------------------
+# Nearest-neighbor interpolation
+#------------------------------------------------------------------------------
+
+
+class NearestNDInterpolator(NDInterpolatorBase):
+    """
+    NearestNDInterpolator(x, y)
+
+    Nearest-neighbor interpolation in N dimensions.
+
+    .. versionadded:: 0.9
+
+    Methods
+    -------
+    __call__
+
+    Parameters
+    ----------
+    x : (Npoints, Ndims) ndarray of floats
+        Data point coordinates.
+    y : (Npoints,) ndarray of float or complex
+        Data values.
+    rescale : boolean, optional
+        Rescale points to unit cube before performing interpolation.
+        This is useful if some of the input dimensions have
+        incommensurable units and differ by many orders of magnitude.
+
+        .. versionadded:: 0.14.0
+    tree_options : dict, optional
+        Options passed to the underlying ``cKDTree``.
+
+        .. versionadded:: 0.17.0
+
+
+    Notes
+    -----
+    Uses ``scipy.spatial.cKDTree``
+
+    """
+
+    def __init__(self, x, y, rescale=False, tree_options=None):
+        NDInterpolatorBase.__init__(self, x, y, rescale=rescale,
+                                    need_contiguous=False,
+                                    need_values=False)
+        if tree_options is None:
+            tree_options = dict()
+        self.tree = cKDTree(self.points, **tree_options)
+        self.values = np.asarray(y)
+
+    def __call__(self, *args):
+        """
+        Evaluate interpolator at given points.
+
+        Parameters
+        ----------
+        xi : ndarray of float, shape (..., ndim)
+            Points where to interpolate data at.
+
+        """
+        xi = _ndim_coords_from_arrays(args, ndim=self.points.shape[1])
+        xi = self._check_call_shape(xi)
+        xi = self._scale_x(xi)
+        dist, i = self.tree.query(xi)
+        return self.values[i]
+
+
+#------------------------------------------------------------------------------
+# Convenience interface function
+#------------------------------------------------------------------------------
+
+def griddata(points, values, xi, method='linear', fill_value=np.nan,
+             rescale=False):
+    """
+    Interpolate unstructured D-D data.
+
+    Parameters
+    ----------
+    points : 2-D ndarray of floats with shape (n, D), or length D tuple of 1-D ndarrays with shape (n,).
+        Data point coordinates.
+    values : ndarray of float or complex, shape (n,)
+        Data values.
+    xi : 2-D ndarray of floats with shape (m, D), or length D tuple of ndarrays broadcastable to the same shape.
+        Points at which to interpolate data.
+    method : {'linear', 'nearest', 'cubic'}, optional
+        Method of interpolation. One of
+
+        ``nearest``
+          return the value at the data point closest to
+          the point of interpolation. See `NearestNDInterpolator` for
+          more details.
+
+        ``linear``
+          tessellate the input point set to N-D
+          simplices, and interpolate linearly on each simplex. See
+          `LinearNDInterpolator` for more details.
+
+        ``cubic`` (1-D)
+          return the value determined from a cubic
+          spline.
+
+        ``cubic`` (2-D)
+          return the value determined from a
+          piecewise cubic, continuously differentiable (C1), and
+          approximately curvature-minimizing polynomial surface. See
+          `CloughTocher2DInterpolator` for more details.
+    fill_value : float, optional
+        Value used to fill in for requested points outside of the
+        convex hull of the input points. If not provided, then the
+        default is ``nan``. This option has no effect for the
+        'nearest' method.
+    rescale : bool, optional
+        Rescale points to unit cube before performing interpolation.
+        This is useful if some of the input dimensions have
+        incommensurable units and differ by many orders of magnitude.
+
+        .. versionadded:: 0.14.0
+
+    Returns
+    -------
+    ndarray
+        Array of interpolated values.
+
+    Notes
+    -----
+
+    .. versionadded:: 0.9
+
+    Examples
+    --------
+
+    Suppose we want to interpolate the 2-D function
+
+    >>> def func(x, y):
+    ...     return x*(1-x)*np.cos(4*np.pi*x) * np.sin(4*np.pi*y**2)**2
+
+    on a grid in [0, 1]x[0, 1]
+
+    >>> grid_x, grid_y = np.mgrid[0:1:100j, 0:1:200j]
+
+    but we only know its values at 1000 data points:
+
+    >>> points = np.random.rand(1000, 2)
+    >>> values = func(points[:,0], points[:,1])
+
+    This can be done with `griddata` -- below we try out all of the
+    interpolation methods:
+
+    >>> from scipy.interpolate import griddata
+    >>> grid_z0 = griddata(points, values, (grid_x, grid_y), method='nearest')
+    >>> grid_z1 = griddata(points, values, (grid_x, grid_y), method='linear')
+    >>> grid_z2 = griddata(points, values, (grid_x, grid_y), method='cubic')
+
+    One can see that the exact result is reproduced by all of the
+    methods to some degree, but for this smooth function the piecewise
+    cubic interpolant gives the best results:
+
+    >>> import matplotlib.pyplot as plt
+    >>> plt.subplot(221)
+    >>> plt.imshow(func(grid_x, grid_y).T, extent=(0,1,0,1), origin='lower')
+    >>> plt.plot(points[:,0], points[:,1], 'k.', ms=1)
+    >>> plt.title('Original')
+    >>> plt.subplot(222)
+    >>> plt.imshow(grid_z0.T, extent=(0,1,0,1), origin='lower')
+    >>> plt.title('Nearest')
+    >>> plt.subplot(223)
+    >>> plt.imshow(grid_z1.T, extent=(0,1,0,1), origin='lower')
+    >>> plt.title('Linear')
+    >>> plt.subplot(224)
+    >>> plt.imshow(grid_z2.T, extent=(0,1,0,1), origin='lower')
+    >>> plt.title('Cubic')
+    >>> plt.gcf().set_size_inches(6, 6)
+    >>> plt.show()
+
+    """
+
+    points = _ndim_coords_from_arrays(points)
+
+    if points.ndim < 2:
+        ndim = points.ndim
+    else:
+        ndim = points.shape[-1]
+
+    if ndim == 1 and method in ('nearest', 'linear', 'cubic'):
+        from .interpolate import interp1d
+        points = points.ravel()
+        if isinstance(xi, tuple):
+            if len(xi) != 1:
+                raise ValueError("invalid number of dimensions in xi")
+            xi, = xi
+        # Sort points/values together, necessary as input for interp1d
+        idx = np.argsort(points)
+        points = points[idx]
+        values = values[idx]
+        if method == 'nearest':
+            fill_value = 'extrapolate'
+        ip = interp1d(points, values, kind=method, axis=0, bounds_error=False,
+                      fill_value=fill_value)
+        return ip(xi)
+    elif method == 'nearest':
+        ip = NearestNDInterpolator(points, values, rescale=rescale)
+        return ip(xi)
+    elif method == 'linear':
+        ip = LinearNDInterpolator(points, values, fill_value=fill_value,
+                                  rescale=rescale)
+        return ip(xi)
+    elif method == 'cubic' and ndim == 2:
+        ip = CloughTocher2DInterpolator(points, values, fill_value=fill_value,
+                                        rescale=rescale)
+        return ip(xi)
+    else:
+        raise ValueError("Unknown interpolation method %r for "
+                         "%d dimensional data" % (method, ndim))