Implementation of histogram2d

Author: AlexanderKalistratov

dpnp/dpnp_iface_histograms.py

@@ -57,7 +57,7 @@
     "digitize",
     "histogram",
     "histogram_bin_edges",
-    "histogram2d"
+    "histogram2d",
     "histogramdd",
 ]
 
@@ -139,6 +139,9 @@ def _is_finite(a):
         return numpy.isfinite(a)
 
     if range is not None:
+        if len(range) != 2:
+            raise ValueError("range argument must consist of 2 elements.")
+
         first_edge, last_edge = range
         if first_edge > last_edge:
             raise ValueError("max must be larger than min in range parameter.")
@@ -753,6 +756,7 @@ def histogram_bin_edges(a, bins=10, range=None, weights=None):
 
 
 def histogram2d(x, y, bins=10, range=None, density=None, weights=None):
+    # pylint: disable=line-too-long
     """
     Compute the bi-dimensional histogram of two data samples.
 
@@ -764,8 +768,10 @@ def histogram2d(x, y, bins=10, range=None, density=None, weights=None):
     y : {dpnp.ndarray, usm_ndarray} of shape (N,)
         An array containing the y coordinates of the points to be
         histogrammed.
-    bins : {int, list of dpnp.ndarray, list of usm_ndarray, sequence of scalars}, optional
-        The bin specification:
+    bins : {int, list of dpnp.ndarray or usm_ndarray, sequence of scalars}, optional
+        Histogram bins.
+
+        The bins specification:
 
         * If int, the number of bins for the two dimensions (nx=ny=bins).
         * If array, the bin edges for the two dimensions
@@ -822,94 +828,73 @@ def histogram2d(x, y, bins=10, range=None, density=None, weights=None):
 
     Examples
     --------
-    >>> import numpy as np
-    >>> from matplotlib.image import NonUniformImage
-    >>> import matplotlib.pyplot as plt
-
-    Construct a 2-D histogram with variable bin width. First define the bin
-    edges:
-
-    >>> xedges = [0, 1, 3, 5]
-    >>> yedges = [0, 2, 3, 4, 6]
-
-    Next we create a histogram H with random bin content:
-
-    >>> x = np.random.normal(2, 1, 100)
-    >>> y = np.random.normal(1, 1, 100)
-    >>> H, xedges, yedges = np.histogram2d(x, y, bins=(xedges, yedges))
-    >>> # Histogram does not follow Cartesian convention (see Notes),
-    >>> # therefore transpose H for visualization purposes.
-    >>> H = H.T
-
-    :func:`imshow <matplotlib.pyplot.imshow>` can only display square bins:
-
-    >>> fig = plt.figure(figsize=(7, 3))
-    >>> ax = fig.add_subplot(131, title='imshow: square bins')
-    >>> plt.imshow(H, interpolation='nearest', origin='lower',
-    ...         extent=[xedges[0], xedges[-1], yedges[0], yedges[-1]])
-    <matplotlib.image.AxesImage object at 0x...>
-
-    :func:`pcolormesh <matplotlib.pyplot.pcolormesh>` can display actual edges:
-
-    >>> ax = fig.add_subplot(132, title='pcolormesh: actual edges',
-    ...         aspect='equal')
-    >>> X, Y = np.meshgrid(xedges, yedges)
-    >>> ax.pcolormesh(X, Y, H)
-    <matplotlib.collections.QuadMesh object at 0x...>
-
-    :class:`NonUniformImage <matplotlib.image.NonUniformImage>` can be used to
-    display actual bin edges with interpolation:
-
-    >>> ax = fig.add_subplot(133, title='NonUniformImage: interpolated',
-    ...         aspect='equal', xlim=xedges[[0, -1]], ylim=yedges[[0, -1]])
-    >>> im = NonUniformImage(ax, interpolation='bilinear')
-    >>> xcenters = (xedges[:-1] + xedges[1:]) / 2
-    >>> ycenters = (yedges[:-1] + yedges[1:]) / 2
-    >>> im.set_data(xcenters, ycenters, H)
-    >>> ax.add_image(im)
-    >>> plt.show()
-
-    It is also possible to construct a 2-D histogram without specifying bin
-    edges:
-
-    >>> # Generate non-symmetric test data
-    >>> n = 10000
-    >>> x = np.linspace(1, 100, n)
-    >>> y = 2*np.log(x) + np.random.rand(n) - 0.5
-    >>> # Compute 2d histogram. Note the order of x/y and xedges/yedges
-    >>> H, yedges, xedges = np.histogram2d(y, x, bins=20)
-
-    Now we can plot the histogram using
-    :func:`pcolormesh <matplotlib.pyplot.pcolormesh>`, and a
-    :func:`hexbin <matplotlib.pyplot.hexbin>` for comparison.
-
-    >>> # Plot histogram using pcolormesh
-    >>> fig, (ax1, ax2) = plt.subplots(ncols=2, sharey=True)
-    >>> ax1.pcolormesh(xedges, yedges, H, cmap='rainbow')
-    >>> ax1.plot(x, 2*np.log(x), 'k-')
-    >>> ax1.set_xlim(x.min(), x.max())
-    >>> ax1.set_ylim(y.min(), y.max())
-    >>> ax1.set_xlabel('x')
-    >>> ax1.set_ylabel('y')
-    >>> ax1.set_title('histogram2d')
-    >>> ax1.grid()
-
-    >>> # Create hexbin plot for comparison
-    >>> ax2.hexbin(x, y, gridsize=20, cmap='rainbow')
-    >>> ax2.plot(x, 2*np.log(x), 'k-')
-    >>> ax2.set_title('hexbin')
-    >>> ax2.set_xlim(x.min(), x.max())
-    >>> ax2.set_xlabel('x')
-    >>> ax2.grid()
-
-    >>> plt.show()
+    >>> import dpnp as np
+    >>> x = np.random.randn(20)
+    >>> y = np.random.randn(20)
+    >>> hist, edges_x, edges_y = np.histogram2d(x, y, bins=(4, 3))
+    >>> hist
+    [[1. 0. 0.]
+     [0. 0. 0.]
+     [5. 6. 4.]
+     [1. 2. 1.]]
+    >>> edges_x
+    [-5.6575713 -3.5574734 -1.4573755  0.6427226  2.74282  ]
+    >>> edges_y
+    [-1.1889046  -0.07263839  1.0436279   2.159894  ]
     """
+    # pylint: enable=line-too-long
+
+    dpnp.check_supported_arrays_type(x, y)
+    if weights is not None:
+        dpnp.check_supported_arrays_type(weights)
+
+    if x.ndim != 1 or y.ndim != 1:
+        raise ValueError(
+            f"x and y must be 1-dimensional arrays."
+            f"Got {x.ndim} and {y.ndim} respectively"
+        )
 
     if len(x) != len(y):
-        raise ValueError(f'x and y must have the same length. Got {len(x)} and {len(y)} respectively')
+        raise ValueError(
+            f"x and y must have the same length."
+            f"Got {len(x)} and {len(y)} respectively"
+        )
+
+    usm_type, exec_q = get_usm_allocations([x, y, bins, range, weights])
+    device = exec_q.sycl_device
+
+    sample_dtype = _result_type_for_device([x.dtype, y.dtype], device)
+
+    # Unlike histogramdd histogram2d accepts 1d bins and
+    # apply it to both dimensions
+    # at the same moment two elements bins should be interpreted as
+    # number of bins in each dimension and array-like bins with one element
+    # is not allowed
+    if isinstance(bins, Iterable) and len(bins) > 2:
+        bins = [bins] * 2
+
+    bins = _histdd_normalize_bins(bins, 2)
+    bins_dtypes = [sample_dtype]
+    bins_dtypes += [b.dtype for b in bins if hasattr(b, "dtype")]
+
+    bins_dtype = _result_type_for_device(bins_dtypes, device)
+    hist_dtype = _histdd_hist_dtype(exec_q, weights)
 
+    supported_types = statistics_ext.histogramdd_dtypes()
+
+    sample_dtype, _ = _align_dtypes(
+        sample_dtype, bins_dtype, hist_dtype, supported_types, device
+    )
 
-    hist, edges = histogramdd([x, y], bins, range, density, weights)
+    sample = dpnp.empty_like(
+        x, shape=x.shape + (2,), dtype=sample_dtype, usm_type=usm_type
+    )
+    sample[:, 0] = x
+    sample[:, 1] = y
+
+    hist, edges = histogramdd(
+        sample, bins=bins, range=range, density=density, weights=weights
+    )
     return hist, edges[0], edges[1]
 
 
@@ -1080,7 +1065,7 @@ def _histdd_extract_arrays(sample, weights, bins):
     return all_arrays
 
 
-def histogramdd(sample, bins=10, range=None, weights=None, density=False):
+def histogramdd(sample, bins=10, range=None, density=False, weights=None):
     """
     Compute the multidimensional histogram of some data.
 
@@ -1155,7 +1140,7 @@ def histogramdd(sample, bins=10, range=None, weights=None, density=False):
     elif sample.ndim > 2:
         raise ValueError("sample must have no more than 2 dimensions")
 
-    ndim = sample.shape[1] if sample.size > 0 else 1
+    ndim = sample.shape[1]
 
     _arrays = _histdd_extract_arrays(sample, weights, bins)
     usm_type, queue = get_usm_allocations(_arrays)