BUG: Use value_count_uint64 in value_counts

Author: gfyoung

pandas/core/algorithms.py

@@ -9,7 +9,9 @@
 from pandas import compat, lib, tslib, _np_version_under1p8
 from pandas.types.cast import _maybe_promote
 from pandas.types.generic import ABCSeries, ABCIndex
-from pandas.types.common import (is_integer_dtype,
+from pandas.types.common import (is_unsigned_integer_dtype,
+                                 is_signed_integer_dtype,
+                                 is_integer_dtype,
                                  is_int64_dtype,
                                  is_categorical_dtype,
                                  is_extension_type,
@@ -471,9 +473,12 @@ def _value_counts_arraylike(values, dropna=True):
         if is_period_type:
             keys = PeriodIndex._simple_new(keys, freq=freq)
 
-    elif is_integer_dtype(dtype):
+    elif is_signed_integer_dtype(dtype):
         values = _ensure_int64(values)
         keys, counts = htable.value_count_int64(values, dropna)
+    elif is_unsigned_integer_dtype(dtype):
+        values = _ensure_uint64(values)
+        keys, counts = htable.value_count_uint64(values, dropna)
     elif is_float_dtype(dtype):
         values = _ensure_float64(values)
         keys, counts = htable.value_count_float64(values, dropna)

pandas/types/common.py

@@ -155,6 +155,18 @@ def is_integer_dtype(arr_or_dtype):
             not issubclass(tipo, (np.datetime64, np.timedelta64)))
 
 
+def is_signed_integer_dtype(arr_or_dtype):
+    tipo = _get_dtype_type(arr_or_dtype)
+    return (issubclass(tipo, np.signedinteger) and
+            not issubclass(tipo, (np.datetime64, np.timedelta64)))
+
+
+def is_unsigned_integer_dtype(arr_or_dtype):
+    tipo = _get_dtype_type(arr_or_dtype)
+    return (issubclass(tipo, np.unsignedinteger) and
+            not issubclass(tipo, (np.datetime64, np.timedelta64)))
+
+
 def is_int64_dtype(arr_or_dtype):
     tipo = _get_dtype_type(arr_or_dtype)
     return issubclass(tipo, np.int64)