BUG/ENH : Column name mangling doesn't strip white space

[rahulporuri]

A small, complete example of the issue

a ,a ,a 
1,2,3
4,5,6
7,8,9

note the white space next to the char.

>>> import pandas
>>> df = pandas.read_table('test.csv', sep=',')
>>> df.columns
Index([u'a ', u'a .1', u'a .2'], dtype='object')

again, note the white space between the char and the num.

A work around previously was to set mangle_dupe_cols to False, manually strip the columns and then clean up the column names. With pandas 0.19.0, mangle_dupe_cols=False raises a ValueError.

This issue is more of a question as to what the spec of mangle_dupe_cols is and what a full implementation, mentioned in #13262 , desires/is going to be.

Expected Output

Index([u'a', u'a.1', u'a.2'], dtype='object')

Output of pd.show_versions()

## INSTALLED VERSIONS

commit: None
python: 2.7.11.final.0
python-bits: 64
OS: Darwin
OS-release: 15.6.0
machine: x86_64
processor: i386
byteorder: little
LC_ALL: en_US.UTF-8
LANG: en_US.UTF-8
LOCALE: None.None

pandas: 0.19.0
nose: 1.3.7
pip: 8.1.2
setuptools: 23.1.0
Cython: 0.24
numpy: 1.10.4
scipy: None
statsmodels: None
xarray: None
IPython: 5.1.0
sphinx: 1.4.1
patsy: None
dateutil: 2.5.2
pytz: 2016.3
blosc: None
bottleneck: None
tables: None
numexpr: None
matplotlib: None
openpyxl: 2.4.0
xlrd: 1.0.0
xlwt: None
xlsxwriter: None
lxml: 3.6.0
bs4: 4.4.1
html5lib: 0.999
httplib2: None
apiclient: None
sqlalchemy: None
pymysql: None
psycopg2: None
jinja2: None
boto: None
pandas_datareader: None

[jorisvandenbossche]

@rahulporuri Those whitespaces are not specific to the duplicate column names:

In [6]: s = """a ,b ,c 
    ...: 1,2,3
    ...: 4,5,6
    ...: 7,8,9"""

In [8]: pd.read_csv(StringIO(s)).columns
Out[8]: Index(['a ', 'b ', 'c '], dtype='object')

But of course, it is true that in this case you can simply strip them from whitespace, and with the mangled columns not.
However, note that previously the read values were just plain wrong with duplicate column names. Therefore the mangle_dupe_columns=False feature is disabled for now.

[jorisvandenbossche]

The idea of mangle_dupe_cols=False would be to read the values correctly, but without the .1 and .2, .. added to the column names (and once this works, you can then strip the whitespace).
If somebody implements it, we would certainly accept a PR to make this work again. But the issue to discuss that is #13262

[jreback]

closing as this is covered by the referenced issues.