.str.replace does not accept a repl function

[hzpc-joostk]

I wanted to pass a function as repl to .str.replace so it was used by re.sub. But it seems that a bug fix for #13438 prevented that to happen. What are your thoughts about this?

Code Sample

s = pd.Series(['foo', 'bar', 'baz'])
s.str.replace(r'[aeiou]', lambda m: m.group().upper())

Problem description

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-26-bc58c5c60bd2> in <module>()
----> 1 s.str.replace(r'[aeiou]', lambda m: m.group().upper())

/anaconda3/lib/python3.4/site-packages/pandas/core/strings.py in replace(self, pat, repl, n, case, flags)
   1504     def replace(self, pat, repl, n=-1, case=True, flags=0):
   1505         result = str_replace(self._data, pat, repl, n=n, case=case,
-> 1506                              flags=flags)
   1507         return self._wrap_result(result)
   1508 

/anaconda3/lib/python3.4/site-packages/pandas/core/strings.py in str_replace(arr, pat, repl, n, case, flags)
    320     # Check whether repl is valid (GH 13438)
    321     if not is_string_like(repl):
--> 322         raise TypeError("repl must be a string")
    323     use_re = not case or len(pat) > 1 or flags
    324 

TypeError: repl must be a string

Expected Output

0    fOO
1    bAr
2    bAz
dtype: object

Output of pd.show_versions()

INSTALLED VERSIONS
------------------
commit: None
python: 3.4.5.final.0
python-bits: 64
OS: Linux
OS-release: 2.6.32-573.3.1.el6.x86_64
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: en_US.UTF-8
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8

pandas: 0.19.0
nose: 1.3.7
pip: 9.0.1
setuptools: 18.1
Cython: 0.25.1
numpy: 1.11.1
scipy: 0.17.1
statsmodels: 0.6.1
xarray: None
IPython: 5.0.0
sphinx: 1.3.1
patsy: 0.4.0
dateutil: 2.4.2
pytz: 2015.7
blosc: None
bottleneck: 1.0.0
tables: 3.2.2
numexpr: 2.6.1
matplotlib: 1.5.0
openpyxl: 2.3.2
xlrd: 0.9.4
xlwt: None
xlsxwriter: None
lxml: 3.5.0
bs4: 4.4.1
html5lib: None
httplib2: None
apiclient: None
sqlalchemy: 1.0.14
pymysql: None
psycopg2: 2.6.1 (dt dec pq3 ext)
jinja2: 2.8
boto: 2.38.0
pandas_datareader: None

[chris-b1]

Yes, this should probably work, and docstring updated to note that it can take a callable, like re.sub. Should be pretty straightforward, PR welcome.