python - Slice Pandas dataframe by index values that are (not) in a list

Question

I have a pandas dataframe, df.

I want to select all indices in df that are not in a list, blacklist.

Now, I use list comprehension to create the desired labels to slice.

ix=[i for i in df.index if i not in blacklist]  
df_select=df.loc[ix]

Works fine, but may be clumsy if I need to do this often.

Is there a better way to do this?

Answer 1

Use isin on the index and invert the boolean index to perform label selection:

In [239]:

df = pd.DataFrame({'a':np.random.randn(5)})
df
Out[239]:
          a
0 -0.548275
1 -0.411741
2 -1.187369
3  1.028967
4 -2.755030
In [240]:

t = [2,4]
df.loc[~df.index.isin(t)]
Out[240]:
          a
0 -0.548275
1 -0.411741
3  1.028967