fix KeyError: "None of [Index(['0_x', '1_x', '0_y', '1_y'], dtype='ob…

…ject')] are in the [columns]"

Added test

dask_image/ndmeasure/_utils/_find_objects.py

@@ -1,7 +1,7 @@
+import dask.dataframe as dd
 import numpy as np
 import pandas as pd
 from dask.delayed import Delayed
-import dask.dataframe as dd
 
 
 def _array_chunk_location(block_id, chunks):
@@ -28,7 +28,8 @@ def _find_bounding_boxes(x, array_location):
  result = {}
  for val in unique_vals:
  positions = np.where(x == val)
- slices = tuple(slice(np.min(pos) + array_location[i], np.max(pos) + 1 + array_location[i]) for i, pos in enumerate(positions))
+ slices = tuple(slice(np.min(pos) + array_location[i], np.max(pos) + 1 + array_location[i]) for i, pos in
+ enumerate(positions))
  result[val] = slices
  column_names = [i for i in range(x.ndim)] # column names are: 0, 1, ... nD
  return pd.DataFrame.from_dict(result, orient='index', columns=column_names)
@@ -70,6 +71,14 @@ def _find_objects(ndim, df1, df2):
  df1 = dd.from_delayed(df1, meta=meta)
  if isinstance(df2, Delayed):
  df2 = dd.from_delayed(df2, meta=meta)
- ddf = dd.merge(df1, df2, how="outer", left_index=True, right_index=True)
+
+ if len(df1) > 0 and len(df2) > 0:
+ ddf = dd.merge(df1, df2, how="outer", left_index=True, right_index=True)
+ elif len(df1) > 0:
+ ddf = df1
+ elif len(df2) > 0:
+ ddf = df2
+ else:
+ ddf = pd.DataFrame()
  result = ddf.apply(_merge_bounding_boxes, ndim=ndim, axis=1, meta=meta)
  return result

tests/test_dask_image/test_ndmeasure/test_find_objects.py

@@ -1,4 +1,3 @@
-from dask_image.ndmeasure._utils import _labeled_comprehension_delayed
 import dask.array as da
 import dask.dataframe as dd
 import numpy as np
@@ -22,9 +21,9 @@ def label_image():
 
  """
  label_image = np.zeros((5, 10)).astype(int)
- label_image[1:3,0:2] = 111
- label_image[3,3:-2] = 222
- label_image[0:2,-3:] = 333
+ label_image[1:3, 0:2] = 111
+ label_image[3, 3:-2] = 222
+ label_image[0:2, -3:] = 333
  label_image = da.from_array(label_image, chunks=(5, 5))
  return label_image
 
@@ -43,8 +42,8 @@ def label_image_with_empty_chunk():
  [ 0, 0, 0, 0, 0, 0]])
  """
  label_image = np.zeros((6, 6)).astype(int)
- label_image[1:3,0:2] = 111
- label_image[4,3:] = 222
+ label_image[1:3, 0:2] = 111
+ label_image[4, 3:] = 222
  label_image = da.from_array(label_image, chunks=(3, 3))
  return label_image
 
@@ -55,14 +54,23 @@ def test_find_objects_err(label_image):
  dask_image.ndmeasure.find_objects(label_image)
 
 
+def test_empty_chunk():
+ test_labels = da.zeros((10, 10), dtype='int', chunks=(3, 3))
+ test_labels[0, 0] = 1
+ computed_result = dask_image.ndmeasure.find_objects(test_labels).compute()
+ expected = pd.DataFrame.from_dict({0: {1: slice(0, 1)},
+ 1: {1: slice(0, 1)}, })
+ assert computed_result.equals(expected)
+
+
 def test_find_objects(label_image):
  result = dask_image.ndmeasure.find_objects(label_image)
  assert isinstance(result, dd.DataFrame)
  computed_result = result.compute()
  assert isinstance(computed_result, pd.DataFrame)
  expected = pd.DataFrame.from_dict(
  {0: {111: slice(1, 3), 222: slice(3, 4), 333: slice(0, 2)},
- 1: {111: slice(0, 2), 222: slice(3, 8), 333: slice(7, 10)}}
+  1: {111: slice(0, 2), 222: slice(3, 8), 333: slice(7, 10)}}
  )
  assert computed_result.equals(expected)
 
@@ -75,8 +83,8 @@ def test_3d_find_objects(label_image):
  assert isinstance(computed_result, pd.DataFrame)
  expected = pd.DataFrame.from_dict(
  {0: {111: slice(1, 3), 222: slice(3, 4), 333: slice(0, 2)},
- 1: {111: slice(0, 2), 222: slice(3, 8), 333: slice(7, 10)},
- 2: {111: slice(0, 2), 222: slice(0, 2), 333: slice(0, 2)}}
+  1: {111: slice(0, 2), 222: slice(3, 8), 333: slice(7, 10)},
+  2: {111: slice(0, 2), 222: slice(0, 2), 333: slice(0, 2)}}
  )
  assert computed_result.equals(expected)
 
@@ -88,6 +96,6 @@ def test_find_objects_with_empty_chunks(label_image_with_empty_chunk):
  assert isinstance(computed_result, pd.DataFrame)
  expected = pd.DataFrame.from_dict(
  {0: {111: slice(1, 3, None), 222: slice(4, 5, None)},
- 1: {111: slice(0, 2, None), 222: slice(3, 6, None)}}
+  1: {111: slice(0, 2, None), 222: slice(3, 6, None)}}
  )
  assert computed_result.equals(expected)