ERR: Add check for input array lengths in from_arrays method (GH13599)

closes #13599

Author: Sahil Dua <[email protected]>

Closes #13728 from sahildua2305/multi-from-arrays-bug and squashes the following commits:

dbd3ab8 [Sahil Dua] BUG: Add check for input array lengths in from_arrays method (GH13599)

Author: sahildua2305

doc/source/whatsnew/v0.19.0.txt

@@ -681,6 +681,7 @@ Bug Fixes
 - Bug in ``DataFrame.to_csv()`` in which float values were being quoted even though quotations were specified for non-numeric values only (:issue:`12922`, :issue:`13259`)
 - Bug in ``MultiIndex`` slicing where extra elements were returned when level is non-unique (:issue:`12896`)
 - Bug in ``.str.replace`` does not raise ``TypeError`` for invalid replacement (:issue:`13438`)
+- Bug in ``MultiIndex.from_arrays`` which didn't check for input array lengths matching (:issue:`13599`)
 
 
 - Bug in ``pd.read_csv()`` with ``engine='python'`` in which ``NaN`` values weren't being detected after data was converted to numeric values (:issue:`13314`)

pandas/indexes/multi.py

@@ -848,6 +848,12 @@ def from_arrays(cls, arrays, sortorder=None, names=None):
             name = None if names is None else names[0]
             return Index(arrays[0], name=name)
 
+        # Check if lengths of all arrays are equal or not,
+        # raise ValueError, if not
+        for i in range(1, len(arrays)):
+            if len(arrays[i]) != len(arrays[i - 1]):
+                raise ValueError('all arrays must be same length')
+
         cats = [Categorical.from_array(arr, ordered=True) for arr in arrays]
         levels = [c.categories for c in cats]
         labels = [c.codes for c in cats]

pandas/tests/indexes/test_multi.py

@@ -632,6 +632,23 @@ def test_from_arrays_index_series_period(self):
 
         tm.assert_index_equal(result, result2)
 
+    def test_from_arrays_different_lengths(self):
+        # GH13599
+        idx1 = [1, 2, 3]
+        idx2 = ['a', 'b']
+        assertRaisesRegexp(ValueError, '^all arrays must be same length$',
+                           MultiIndex.from_arrays, [idx1, idx2])
+
+        idx1 = []
+        idx2 = ['a', 'b']
+        assertRaisesRegexp(ValueError, '^all arrays must be same length$',
+                           MultiIndex.from_arrays, [idx1, idx2])
+
+        idx1 = [1, 2, 3]
+        idx2 = []
+        assertRaisesRegexp(ValueError, '^all arrays must be same length$',
+                           MultiIndex.from_arrays, [idx1, idx2])
+
     def test_from_product(self):
 
         first = ['foo', 'bar', 'buz']