add error if drop_index is negative (dask#8064)

marcelned · Sep 13, 2021 · 9f0b00f · 9f0b00f
1 parent 618aedf
commit 9f0b00f
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/dask/array/core.py b/dask/array/core.py
@@ -694,6 +694,8 @@ def map_blocks(
         dtype = apply_infer_dtype(func, args, original_kwargs, "map_blocks")
 
     if drop_axis:
+        if any(i < 0 for i in drop_axis):
+            raise ValueError(f"Expected drop_axis to be non-negative; got {drop_axis}.")
         out_ind = tuple(x for i, x in enumerate(out_ind) if i not in drop_axis)
     if new_axis is None and chunks is not None and len(out_ind) < len(chunks):
         new_axis = range(len(chunks) - len(out_ind))