pandas function with isin

Question

I have a dataframe as like this:

aa        bb  cc
[a, x, y] a   1
[b, d, z] b   2
[c, e, f] s   3
np.nan    d   4

I'm trying to create a new column like this:

aa        bb  cc dd
[a, x, y] a   1  True
[b, d, z] b   2  True
[c, e, f] s   3  False
np.nan    d   4  False

My current solution is:

def some_function(row):
    if row['bb].isin(row['aa'])==True:
        return True
    return False
df['dd'] = df.apply(lambda row: some_function(row), axis=1)

But this throws out an error ("'str' object has no attribute 'isin'", 'occurred at index 0')

I suspect, because I'm missing something when it comes to checking the isin.

Essentially, I need to check if the str value of bb is in column aa which has a list in each cell.

Any ideas on how to do this?

Answer 1

You need parameter in for check membership in list:

df['dd'] = df.apply(lambda x: x.bb in x.aa, axis=1)
print (df)
          aa bb  cc     dd
0  [a, x, y]  a   1   True
1  [b, d, z]  b   2   True
2  [c, e, f]  s   3  False

EDIT:

df['dd'] = df.apply(lambda x: (x.bb in x.aa) and (x.cc == 1), axis=1) 
print (df)
          aa bb  cc     dd
0  [a, x, y]  a   1   True
1  [b, d, z]  b   2  False
2  [c, e, f]  s   3  False

Or:

df['dd'] = df.apply(lambda x: x.bb in x.aa, axis=1) & (df['cc'] == 1)
print (df)
          aa bb  cc     dd
0  [a, x, y]  a   1   True
1  [b, d, z]  b   2  False
2  [c, e, f]  s   3  False

EDIT:

df['dd'] = df.apply(lambda x: x.bb in x.aa if type(x.aa) == list else False, axis=1) 
print (df)
          aa bb  cc     dd
0  [a, x, y]  a   1   True
1  [b, d, z]  b   2   True
2  [c, e, f]  s   3  False
4        NaN  d   4  False