理解力
[a in b for a, b in zip(df.a, df.b)]
[True, False, True, False, True]
df.assign(In=[a in b for a, b in zip(df.a, df.b)])
a b In
0 a a/b True
1 b c/d False
2 c c/a True
3 d a/b False
4 e e True
from numpy.core.defchararray import find
a, b = df.values.astype(str).T
find(b, a) >= 0
array([ True, False, True, False, True])
df.assign(In=find(b, a) >= 0)
a b In
0 a a/b True
1 b c/d False
2 c c/a True
3 d a/b False
4 e e True