🐛 Fix erroneous concat when n_chunks=1 on axis=1 apply (#9)

ddelange · Feb 17, 2021 · 0306dfb · 0306dfb
1 parent 8f966a4
commit 0306dfb
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Showing 2 changed files with 13 additions and 1 deletion.
diff --git a/src/mapply/mapply.py b/src/mapply/mapply.py
@@ -116,7 +116,11 @@ def run_apply(func, df_or_series, args=(), **kwargs):
  progressbar=progressbar,
  )
 
- if not isseries and results[0].index.equals(df_or_series.index):
+ if (
+ not isseries
+ and len(results) > 1
+ and results[0].index.equals(df_or_series.index)
+ ):
  return concat(results, axis=1, copy=False)
 
  return concat(results, copy=False)
diff --git a/tests/test_mapply.py b/tests/test_mapply.py
@@ -57,6 +57,14 @@ def test_df_mapply():
  df.mapply(lambda x: x ** 2),
  )
 
+ # concat for only one result
+ mapply.init(progressbar=False, chunk_size=100, n_workers=2)
+ df = pd.DataFrame(list(range(1, 200))) # (199, 1)
+ pd.testing.assert_series_equal(
+ df.apply(sum, axis=1),
+ df.mapply(sum, axis=1),
+ )
+
 
 def test_series_mapply():
  # chunk_size>1