BUG: dtype=str in 0.23.0 converts NaN to 'n' · Issue #22477 · pandas-dev/pandas (original) (raw)

import pandas as pd series = pd.Series(index=range(5), dtype=str) series 0 n 1 n 2 n 3 n 4 n dtype: object pd.show_versions()

INSTALLED VERSIONS

commit: None python: 3.6.0.final.0 python-bits: 64 OS: Darwin OS-release: 14.3.0 machine: x86_64 processor: i386 byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: en_US.UTF-8

pandas: 0.23.0 pytest: 3.0.5 pip: 9.0.1 setuptools: 40.0.0 Cython: 0.25.2 numpy: 1.11.3 scipy: 0.18.1 pyarrow: None xarray: None IPython: 5.1.0 sphinx: 1.5.1 patsy: 0.4.1 dateutil: 2.6.0 pytz: 2016.10 blosc: None bottleneck: 1.2.0 tables: 3.3.0 numexpr: 2.6.1 feather: None matplotlib: 2.0.0 openpyxl: 2.4.1 xlrd: 1.0.0 xlwt: 1.2.0 xlsxwriter: 0.9.6 lxml: 3.7.2 bs4: 4.5.3 html5lib: None sqlalchemy: 1.1.5 pymysql: None psycopg2: None jinja2: 2.9.4 s3fs: None fastparquet: None pandas_gbq: None pandas_datareader: None

Before I upgraded pandas to 0.23.0, pd.Series(dtype=str, index=range(5)) gave me a series filled with NaN values. However, with this recent upgrade, dtype=str converts null values to lower case letter ’n’. I’m appending the normal null value series output below as a comparison.

import pandas as pd series = pd.Series(index=range(5), dtype=str) series 0 NaN 1 NaN 2 NaN 3 NaN 4 NaN dtype: object pd.show_versions()

INSTALLED VERSIONS

commit: None python: 3.6.0.final.0 python-bits: 64 OS: Darwin OS-release: 14.3.0 machine: x86_64 processor: i386 byteorder: little LC_ALL: None LANG: en_US.UTF-8 LOCALE: en_US.UTF-8

pandas: 0.22.0 pytest: 3.0.5 pip: 9.0.1 setuptools: 40.0.0 Cython: 0.25.2 numpy: 1.11.3 scipy: 0.18.1 pyarrow: None xarray: None IPython: 5.1.0 sphinx: 1.5.1 patsy: 0.4.1 dateutil: 2.6.0 pytz: 2016.10 blosc: None bottleneck: 1.2.0 tables: 3.3.0 numexpr: 2.6.1 feather: None matplotlib: 2.0.0 openpyxl: 2.4.1 xlrd: 1.0.0 xlwt: 1.2.0 xlsxwriter: 0.9.6 lxml: 3.7.2 bs4: 4.5.3 html5lib: None sqlalchemy: 1.1.5 pymysql: None psycopg2: None jinja2: 2.9.4 s3fs: None fastparquet: None pandas_gbq: None pandas_datareader: None