int64 Index in 0.17 typcasts '0' string to integer #11836
Description
Here's what I got. Is this expected behavior? I could not find a reference for this functionality in the release notes.
0.16
conda create -n pd pandas=0.16 python=3.4 ipython
In 0.16 the dtype of the index changes to object when adding a row with '0'.
In [1]: import pandas as pd In [2]: import numpy as np In [3]: data = np.random.random(10) In [4]: m=pd.Series(data) In [5]: m[0]=0.4444 In [6]: m.index Out[6]: Int64Index([0, 1, 2, 3, 4, 5, 6, 7, 8, 9], dtype='int64') In [7]: m['0']=0.5555 In [8]: m.index Out[8]: Index([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, '0'], dtype='object') 0.17.1
conda create -n pd pandas=0.17 python=3.4 ipython
In 0.17.1 The index dtype does not change, but typecasts to the integer 0. Repeated assignment at the integer 0 index appends more 0s to the index.
In [1]: import pandas as pd In [2]: import numpy as np In [3]: data = np.random.random(10) In [4]: m=pd.Series(data) In [5]: m[0]=0.4444 In [6]: m.index Out[6]: Int64Index([0, 1, 2, 3, 4, 5, 6, 7, 8, 9], dtype='int64') In [7]: m['0']=0.5555 In [8]: m.index Out [8]: Int64Index([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0], dtype='int64') In [9]: m['0']=0.6666 In [10]: m.index Out[10]: Int64Index([0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0], dtype='int64') In [11]: m[0] Out[11]: 0 0.4444 0 0.5555 0 0.6666 dtype: float64