Pandas: Replace Column Values To Empty If Not Present In Pre-defined List

I have a list, X, that contains a set of legal values for a column. Say, I have column A. I want to replace (set to empty string) elements in df['A'] if their value is not in X. Ho

Solution 1:

try this:

df.loc[~df.A.isin(X), 'A'] = ''

Solution 2:

You can do it with apply:

import pandas as pd

x = ['a', 'b', 'c']
data = {'foo':['a', 'a', 'q', 'p']}
df = pd.DataFrame.from_dict(data)

df_new = df['foo'].apply(lambda i: i if i in x else'')