Reapply perf improvement that was struck from pandas-dev#22725

h-vetinari · Oct 30, 2018 · 2f94c13 · 2f94c13
1 parent b07298d
commit 2f94c13
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/pandas/core/strings.py b/pandas/core/strings.py
@@ -54,6 +54,8 @@ def cat_core(list_of_columns, sep):
     nd.array
         The concatenation of list_of_columns with sep
     """
+    if sep == '':
+        return np.sum(list_of_columns, axis=0)
     list_with_sep = [sep] * (2 * len(list_of_columns) - 1)
     list_with_sep[::2] = list_of_columns
     return np.sum(list_with_sep, axis=0)