Fix coordinate ordering of Image returned by _colorize [#792]

datashader/tests/test_transfer_functions.py

@@ -6,11 +6,11 @@
 import xarray as xr
 import PIL
 import pytest
-
+from collections import OrderedDict
 import datashader.transfer_functions as tf
 
 
-coords = [np.array([0, 1, 2]), np.array([3, 4, 5])]
+coords = OrderedDict([('x_axis', [3, 4, 5]), ('y_axis', [0, 1, 2])])
 dims = ['y_axis', 'x_axis']
 
 a = np.arange(10, 19, dtype='i4').reshape((3, 3))
@@ -111,6 +111,9 @@ def test_shade(attr, span):
     img = tf.shade(x, cmap=cmap, how='log', span=span)
     sol = solutions['log']
     assert img.equals(sol)
+    # Check dims/coordinates order
+    assert list(img.coords) == ['x_axis', 'y_axis']
+    assert list(img.dims) == ['y_axis', 'x_axis']
 
     img = tf.shade(x, cmap=cmap, how='cbrt', span=span)
     sol = solutions['cbrt']
@@ -250,6 +253,9 @@ def test_shade_category():
                     [4283774890, 3707764991]], dtype='u4')
     sol = tf.Image(sol, coords=coords, dims=dims)
     assert img.equals(sol)
+    # Check dims/coordinates order
+    assert list(img.coords) == ['x_axis', 'y_axis']
+    assert list(img.dims) == ['y_axis', 'x_axis']
 
     colors = dict(zip('abc', colors))
 

datashader/transfer_functions.py

@@ -1,6 +1,6 @@
 from __future__ import absolute_import, division, print_function
 
-from collections import Iterator
+from collections import Iterator, OrderedDict
 from io import BytesIO
 
 import numpy as np
@@ -288,8 +288,14 @@ def _colorize(agg, color_key, how, min_alpha, name):
     a = np.interp(a, [np.nanmin(a), np.nanmax(a)],
                   [min_alpha, 255], left=0, right=255).astype(np.uint8)
     r[mask] = g[mask] = b[mask] = 255
-    return Image(np.dstack([r, g, b, a]).view(np.uint32).reshape(a.shape),
-                 dims=agg.dims[:-1], coords=list(agg.coords.values())[:-1],
+    values = np.dstack([r, g, b, a]).view(np.uint32).reshape(a.shape)
+
+    return Image(values,
+                 dims=agg.dims[:-1],
+                 coords=OrderedDict([
+                     (agg.dims[1], agg.coords[agg.dims[1]]),
+                     (agg.dims[0], agg.coords[agg.dims[0]]),
+                 ]),
                  name=name)