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pythonpandasdataframekeyerror

Python Pandas : Select data and ignoring KeyErrors

Note: my question isn't this one, but something a little more subtle.

Say I have a dataframe that looks like this

df = 
    A     B    C
0   3     3    1
1   2     1    9

df[["A", "B", "D"]] will raise a KeyError.

Is there a python pandas way to let df[["A", "B", "D"]] == df[["A", "B"]]? (Ie: just select the columns that exist.)

One solution might be

good_columns = list(set(df.columns).intersection(["A", "B", "D"]))
mydf = df[good_columns]

But this has two problems:

  • It's clunky and inelegant.
  • The ordering of mydf.columns could be ["A", "B"] or ["B", "A"].
Solution

  • You can use filter, this will just ignore any extra keys:

    df.filter(["A","B","D"])
    A     B  
0   3     3   
1   2     1