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unstack() on DataFrame of ints with MultiIndex which was sliced casts to float #17845

toobaz opened this Issue Oct 11, 2017 · 1 comment


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3 participants

toobaz commented Oct 11, 2017

Code Sample, a copy-pastable example if possible

In [2]: idx = pd.MultiIndex.from_product([['a'], ['A', 'B', 'C', 'D']])[:-1]

In [3]: df = pd.DataFrame([[1, 0]]*3, index=idx)

In [4]: df.unstack()
     0              1          
     A    B    C    A    B    C
a  1.0  1.0  1.0  0.0  0.0  0.0

Problem description

Since there is no missing value, no type casting should occur. Notice that even replacing index=idx with index=idx.copy(deep=True) doesn't help (something which would maybe require a fix on its own).

Expected Output

In [5]: df.unstack(fill_value=3)
   0        1      
   A  B  C  A  B  C
a  1  1  1  0  0  0

Output of pd.show_versions()


commit: None
python-bits: 64
OS: Linux
OS-release: 4.9.0-3-amd64
machine: x86_64
byteorder: little
LC_ALL: None

pytest: 3.0.6
pip: 9.0.1
setuptools: None
Cython: 0.25.2
numpy: 1.12.1
scipy: 0.19.0
pyarrow: None
xarray: None
sphinx: 1.5.6
patsy: 0.4.1
dateutil: 2.6.0
pytz: 2017.2
blosc: None
bottleneck: 1.2.1
tables: 3.3.0
numexpr: 2.6.1
feather: 0.3.1
matplotlib: 2.0.2
openpyxl: None
xlrd: 1.0.0
xlwt: 1.1.2
xlsxwriter: 0.9.6
lxml: None
bs4: 4.5.3
html5lib: 0.999999999
sqlalchemy: 1.0.15
pymysql: None
psycopg2: None
jinja2: 2.9.6
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: 0.2.1

@gfyoung gfyoung added the Reshaping label Oct 12, 2017


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jreback commented Oct 13, 2017

IIRC there are several related / like issues to this, see if you can find them. note that (though not as satisfying). Yes in thins case you have a full cartesian product so you know there are no missing values, but generally this is not true.

In [33]: df.unstack(fill_value=0)
   0        1      
   A  B  C  A  B  C
a  1  1  1  0  0  0

@jreback jreback added the Dtypes label Oct 13, 2017

@jreback jreback added this to the 0.22.0 milestone Nov 24, 2017

jreback added a commit that referenced this issue Jan 16, 2018

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