This is not a real 'bug' maybe? But it can be annoying.

xref #12614. Independent of issue #12642.

Code Sample

a = np.array(['foo', 'foo', 'foo', 'bar', 'bar', 'foo', 'foo'], dtype=object)
b = np.array(['one', 'one', 'two', 'one', 'two', 'two', 'two'], dtype=object)
c = np.array(['dull', 'dull', 'dull', 'dull', 'dull', 'shiny', 'shiny'], dtype=object)
res_dropnaF = pd.crosstab(a, [b, c], rownames=['a'], colnames=['b', 'c'], dropna=False)
res_dropnaT = pd.crosstab(a, [b, c], rownames=['a'], colnames=['b', 'c'], dropna=True)
print res_dropnaF, '\n\n', res_dropnaT

Results: res_dropnaF shows nocolumns.names (because they're removed) while res_dropnaT does.

     one        two      
    dull shiny dull shiny
a                        
bar    1     0    1     0
foo    2     0    1     2 

b    one  two      
c   dull dull shiny
a                  
bar    1    1     0
foo    2    1     2

Expected Output

Extra option or consistency on column names. Should be fixed by working on pivot_table(): if not dropna

output of pd.show_versions()

INSTALLED VERSION:

commit: None python: 2.7.10.final.0 python-bits: 64 OS: Darwin OS-release: 14.5.0 machine: x86_64 processor: i386 byteorder: little LC_ALL: None LANG: en_US.UTF-8

pandas: 0.17.1 nose: 1.3.3 pip: 8.1.0 setuptools: 18.3.1 Cython: 0.23.4 numpy: 1.10.1 scipy: 0.14.0 statsmodels: 0.5.0 IPython: 2.1.0 sphinx: None patsy: 0.2.1 dateutil: 2.4.2 pytz: 2015.7 blosc: None bottleneck: None tables: None numexpr: None matplotlib: 1.3.1 openpyxl: None xlrd: None xlwt: None xlsxwriter: None lxml: None bs4: None html5lib: None httplib2: None apiclient: None sqlalchemy: None pymysql: None psycopg2: None Jinja2: None

Comment From: jreback

dupe of #12133

Comment From: jreback

fix in #12327 (though that appears stalled)

Comment From: jreback

@OXPHOS so happy to have that fixed up

Comment From: OXPHOS

@jreback Aha good to know! I am wondering whether we still need the fix in #12643 ? I can test later if necessary.

Comment From: jreback

maybe not let's see if the other PR fixes btw happy to have j pick up that PR