Pandas dataframe eval

[poeticcode01]

Code Sample, a copy-pastable example if possible

# Your code here
Scenario 1:

df2=pd.DataFrame({'a1':[10,20]})

df2.eval("c=((a1>10) & True )")
Out[8]: 
   a1      c
0  10  False
1  20   True
Scenario 2:
df2=pd.DataFrame({'a1':['Y','N']})
df2.eval("c=((a1 == 'Y') & True )")
Traceback (most recent call last):

TypeError: issubclass() arg 1 must be a class

Problem description

[this should explain why the current behaviour is a problem and why the expected output is a better solution.]
By changing datatype of a column from int to str, pd.eval throws "TypeError: issubclass() arg 1 must be a class"

Note: We receive a lot of issues on our GitHub tracker, so it is very possible that your issue has been posted before. Please check first before submitting so that we do not have to handle and close duplicates!

Note: Many problems can be resolved by simply upgrading pandas to the latest version. Before submitting, please check if that solution works for you. If possible, you may want to check if master addresses this issue, but that is not necessary.

For documentation-related issues, you can check the latest versions of the docs on master here:

https://pandas-docs.github.io/pandas-docs-travis/

If the issue has not been resolved there, go ahead and file it in the issue tracker.

Expected Output

In Scenario 2

a1 c
10 True
20 False

Output of pd.show_versions()

[paste the output of pd.show_versions() here below this line]
INSTALLED VERSIONS

commit: None
python: 2.7.13.final.0
python-bits: 64
OS: Windows
OS-release: 10
machine: AMD64
processor: Intel64 Family 6 Model 78 Stepping 3, GenuineIntel
byteorder: little
LC_ALL: None
LANG: en
LOCALE: None.None

pandas: 0.21.1
pytest: 3.0.7
pip: 9.0.1
setuptools: 27.2.0
Cython: 0.25.2
numpy: 1.14.2
scipy: 0.19.0
pyarrow: None
xarray: None
IPython: 5.3.0
sphinx: 1.5.6
patsy: 0.4.1
dateutil: 2.6.0
pytz: 2017.2
blosc: None
bottleneck: 1.2.1
tables: 3.2.2
numexpr: 2.6.2
feather: None
matplotlib: 2.0.2
openpyxl: 2.4.7
xlrd: 1.0.0
xlwt: 1.2.0
xlsxwriter: 0.9.6
lxml: 3.7.3
bs4: 4.6.0
html5lib: 0.999
sqlalchemy: 1.1.9
pymysql: None
psycopg2: None
jinja2: 2.9.6
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None

[jreback]

this is a duplicate issue

[poeticcode01]

can u @jreback provide the solution to handle this?