How to compare pandas DataFrame against None in Python?
How do I compare a pandas DataFrame with None? I have a constructor that takes one of a parameter_file or a pandas_df but never both.
def __init__(self,copasi_file,row_to_insert=0,parameter_file=None,pandas_df=None): self.copasi_file=copasi_file self.parameter_file=parameter_file self.pandas_df=pandas_df
However, when I later try to compare the pandas_df against None, (i.e. when self.pandas_df actually contains a pandas dataframe):
if self.pandas_df!=None: print 'Do stuff'
I get the following TypeError:
File "C:\Anaconda1\lib\site-packages\pandas\core\internals.py", line 885, in eval % repr(other)) TypeError: Could not compare [None] with block values
Use is not:
if self.pandas_df is not None: print 'Do stuff'
PEP 8 says:
Comparisons to singletons like None should always be done with is or is not, never the equality operators.
There is also a nice explanation why.