Check if column value is in other columns in pandas

Question

I have the following dataframe in pandas

  target   A       B      C
0 cat      bridge  cat    brush  
1 brush    dog     cat    shoe
2 bridge   cat     shoe         


        

Answer 1

you can use apply a function for each row that counts the number of value that match the value in the 'target' column:

df["exist"] = df.apply(lambda row:row.value_counts()[row['target']] > 1 , axis=1)

for a dataframe that looks like:

   b  c target
0  3  a      a
1  3  4      2
2  3  4      2
3  3  4      2
4  3  4      4

the output will be:

   b  c target  exist
0  3  a      a   True
1  3  4      2  False
2  3  4      2  False
3  3  4      2  False
4  3  4      4   True