Python pandas Filtering out nan from a data selection of a column of strings

Question

Without using groupby how would I filter out data without NaN  Let say I have a matrix where customers will fill in  N A   n a  or any of its variations and others leave it blank  import pandas as pd import numpy as np   df   pd DataFrame   movie     thg    thg    mol    mol    lob    lob                       rating    3   4   5   np nan  np nan  np nan                      name     John   np nan   N A    Graham   np nan  np nan     nbs   df  name   str extract    N A NA na n a    nms df  df  name      nbs     output   gt  gt  gt  nms   movie    name  rating 0   thg    John       3 1   thg     NaN       4 3   mol  Graham     NaN 4   lob     NaN     NaN 5   lob     NaN     NaN  How would I filter out NaN values so I can get results to work with like this    movie    name  rating 0   thg    John       3 3   mol  Graham     NaN  I am guessing I need something like  np isnan but the tilda does not work with strings

User · Answer

df   pd DataFrame   movie     thg    thg    mol    mol    lob    lob    rating    3   4   5   np nan  np nan  np nan   name     John   James   np nan  np nan  np nan np nan     for col in df columns      df   df  pd isnull df col

User · Answer

Just drop them   nms dropna thresh 2    this will drop all rows where there are at least two non-NaN   Then you could then drop where name is NaN   In  87    nms Out 87     movie    name  rating 0   thg    John       3 1   thg     NaN       4 3   mol  Graham     NaN 4   lob     NaN     NaN 5   lob     NaN     NaN   5 rows x 3 columns  In  89    nms   nms dropna thresh 2  In  90    nms nms name notnull    Out 90     movie    name  rating 0   thg    John       3 3   mol  Graham     NaN   2 rows x 3 columns    EDIT  Actually looking at what you originally want you can do just this without the dropna call   nms nms name notnull      UPDATE  Looking at this question 3 years later  there is a mistake  firstly thresh arg looks for at least n non-NaN values so in fact the output should be   In  4   nms dropna thresh 2   Out 4     movie    name  rating 0   thg    John     3 0 1   thg     NaN     4 0 3   mol  Graham     NaN   It s possible that I was either mistaken 3 years ago or that the version of pandas I was running had a bug  both scenarios are entirely possible

User · Answer

df dropna subset   columnName1    columnName2

User · Answer

Simplest of all solutions   filtered df   df df  name   notnull      Thus  it filters out only rows that doesn t have NaN values in  name  column   For multiple columns   filtered df   df df   name    country    region    notnull   all 1

[python] Python pandas Filtering out nan from a data selection of a column of strings

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