Merge pull request #9439 from sinhrks/string_isnumeric

ENH: Add StringMethods.isnumeric and isdecimal

Author: jreback

doc/source/api.rst

@@ -559,6 +559,8 @@ strings and apply several methods to it. These can be acccessed like
    Series.str.islower
    Series.str.isupper
    Series.str.istitle
+   Series.str.isnumeric
+   Series.str.isdecimal
    Series.str.get_dummies
 
 .. _api.categorical:

doc/source/text.rst

@@ -238,3 +238,5 @@ Method Summary
     :meth:`~Series.str.islower`,Equivalent to ``str.islower``
     :meth:`~Series.str.isupper`,Equivalent to ``str.isupper``
     :meth:`~Series.str.istitle`,Equivalent to ``str.istitle``
+    :meth:`~Series.str.isnumeric`,Equivalent to ``str.isnumeric``
+    :meth:`~Series.str.isnumeric`,Equivalent to ``str.isdecimal``

doc/source/whatsnew/v0.16.0.txt

@@ -157,7 +157,7 @@ Enhancements
   ``isupper()``, ``istitle()`` which behave as the same as standard ``str`` (:issue:`9282`)
 
 
-
+- Added ``StringMethods.isnumeric`` and ``isdecimal`` which behave as the same as standard ``str`` (:issue:`9439`)
 - Added ``StringMethods.ljust()`` and ``rjust()`` which behave as the same as standard ``str`` (:issue:`9352`)
 - ``StringMethods.pad()`` and ``center()`` now accept ``fillchar`` option to specify filling character (:issue:`9352`)
 - Added ``StringMethods.zfill()`` which behave as the same as standard ``str`` (:issue:`9387`)

pandas/core/strings.py

@@ -1096,23 +1096,37 @@ def get_dummies(self, sep='|'):
                            docstring=_shared_docs['casemethods'] % 'titlecase')
 
     _shared_docs['ismethods'] = ("""
-    Check whether all characters in each string in the array are %s
+    Check whether all characters in each string in the array are %(type)s.
+    Equivalent to ``str.%(method)s``.
 
     Returns
     -------
     Series of boolean values
     """)
+    _shared_docs['isalnum'] = dict(type='alphanumeric', method='isalnum')
+    _shared_docs['isalpha'] = dict(type='alphabetic', method='isalpha')
+    _shared_docs['isdigit'] = dict(type='digits', method='isdigit')
+    _shared_docs['isspace'] = dict(type='whitespace', method='isspace')
+    _shared_docs['islower'] = dict(type='lowercase', method='islower')
+    _shared_docs['isupper'] = dict(type='uppercase', method='isupper')
+    _shared_docs['istitle'] = dict(type='titlecase', method='istitle')
+    _shared_docs['isnumeric'] = dict(type='numeric', method='isnumeric')
+    _shared_docs['isdecimal'] = dict(type='decimal', method='isdecimal')
     isalnum = _noarg_wrapper(lambda x: x.isalnum(),
-                             docstring=_shared_docs['ismethods'] % 'alphanumeric')
+                             docstring=_shared_docs['ismethods'] % _shared_docs['isalnum'])
     isalpha = _noarg_wrapper(lambda x: x.isalpha(),
-                             docstring=_shared_docs['ismethods'] % 'alphabetic')
+                             docstring=_shared_docs['ismethods'] % _shared_docs['isalpha'])
     isdigit = _noarg_wrapper(lambda x: x.isdigit(),
-                             docstring=_shared_docs['ismethods'] % 'digits')
+                             docstring=_shared_docs['ismethods'] % _shared_docs['isdigit'])
     isspace = _noarg_wrapper(lambda x: x.isspace(),
-                             docstring=_shared_docs['ismethods'] % 'whitespace')
+                             docstring=_shared_docs['ismethods'] % _shared_docs['isspace'])
     islower = _noarg_wrapper(lambda x: x.islower(),
-                             docstring=_shared_docs['ismethods'] % 'lowercase')
+                             docstring=_shared_docs['ismethods'] % _shared_docs['islower'])
     isupper = _noarg_wrapper(lambda x: x.isupper(),
-                             docstring=_shared_docs['ismethods'] % 'uppercase')
+                             docstring=_shared_docs['ismethods'] % _shared_docs['isupper'])
     istitle = _noarg_wrapper(lambda x: x.istitle(),
-                             docstring=_shared_docs['ismethods'] % 'titlecase')
+                             docstring=_shared_docs['ismethods'] % _shared_docs['istitle'])
+    isnumeric = _noarg_wrapper(lambda x: compat.u_safe(x).isnumeric(),
+                             docstring=_shared_docs['ismethods'] % _shared_docs['isnumeric'])
+    isdecimal = _noarg_wrapper(lambda x: compat.u_safe(x).isdecimal(),
+                             docstring=_shared_docs['ismethods'] % _shared_docs['isdecimal'])

pandas/tests/test_strings.py

@@ -14,7 +14,7 @@
 from numpy.testing import assert_array_equal
 from numpy.random import randint
 
-from pandas.compat import range, lrange, u
+from pandas.compat import range, lrange, u, unichr
 import pandas.compat as compat
 from pandas import (Index, Series, TimeSeries, DataFrame, isnull, notnull,
                     bdate_range, date_range, MultiIndex)
@@ -630,6 +630,8 @@ def test_empty_str_methods(self):
         tm.assert_series_equal(empty_str, empty.str.islower())
         tm.assert_series_equal(empty_str, empty.str.isupper())
         tm.assert_series_equal(empty_str, empty.str.istitle())
+        tm.assert_series_equal(empty_str, empty.str.isnumeric())
+        tm.assert_series_equal(empty_str, empty.str.isdecimal())
 
     def test_ismethods(self):
         values = ['A', 'b', 'Xy', '4', '3A', '', 'TT', '55', '-', '  ']
@@ -659,6 +661,31 @@ def test_ismethods(self):
         self.assertEquals(str_s.str.isupper().tolist(), [v.isupper() for v in values])
         self.assertEquals(str_s.str.istitle().tolist(), [v.istitle() for v in values])
 
+    def test_isnumeric(self):
+        # 0x00bc: ¼ VULGAR FRACTION ONE QUARTER
+        # 0x2605: ★ not number
+        # 0x1378: ፸ ETHIOPIC NUMBER SEVENTY
+        # 0xFF13: ３ Em 3
+        values = ['A', '3', unichr(0x00bc), unichr(0x2605),
+                  unichr(0x1378), unichr(0xFF13), 'four']
+        s = Series(values)
+        numeric_e = [False, True, True, False, True, True, False]
+        decimal_e = [False, True, False, False, False, True, False]
+        tm.assert_series_equal(s.str.isnumeric(), Series(numeric_e))
+        tm.assert_series_equal(s.str.isdecimal(), Series(decimal_e))
+        unicodes = [u('A'), u('3'), unichr(0x00bc), unichr(0x2605),
+                  unichr(0x1378), unichr(0xFF13), u('four')]
+        self.assertEquals(s.str.isnumeric().tolist(), [v.isnumeric() for v in unicodes])
+        self.assertEquals(s.str.isdecimal().tolist(), [v.isdecimal() for v in unicodes])
+
+        values = ['A', np.nan, unichr(0x00bc), unichr(0x2605),
+                  np.nan, unichr(0xFF13), 'four']
+        s = Series(values)
+        numeric_e = [False, np.nan, True, False, np.nan, True, False]
+        decimal_e = [False, np.nan, False, False, np.nan, True, False]
+        tm.assert_series_equal(s.str.isnumeric(), Series(numeric_e))
+        tm.assert_series_equal(s.str.isdecimal(), Series(decimal_e))
+
     def test_get_dummies(self):
         s = Series(['a|b', 'a|c', np.nan])
         result = s.str.get_dummies('|')