How to filter in NaN pandas

Question

I have a pandas dataframe  df   and I want to do something like   newdf   df  df var1     a    amp   df var2    NaN     I ve tried replacing NaN with np NaN  or  NaN  or  nan  etc  but nothing evaluates to True  There s no pd NaN   I can use df fillna np nan  before evaluating the above expression but that feels hackish and I wonder if it will interfere with other pandas operations that rely on being able to identify pandas-format NaN s later   I get the feeling there should be an easy answer to this question  but somehow it has eluded me  Any advice is appreciated  Thank you

User · Accepted Answer

This doesn t work because NaN isn t equal to anything  including NaN  Use pd isnull df var2  instead

User · Answer

Simplest of all solutions  filtered df   df df  var2   isnull     This filters and gives you rows which has only NaN values in  var2  column

User · Answer

Pandas uses numpy s NaN value  Use numpy isnan to obtain a Boolean vector from a pandas series

[python] How to filter in NaN (pandas)?

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