使用条件的子集 df - pandas

Question

I'm aiming to subset a df using two conditions. Those being, return rows only when string values in L2 are after by a value in L1 and are followed by a value in L1 .

df = pd.DataFrame({  
    'col_1' : ['a','m','x','b','n','c','c','o','y','a','m','c'],                             
    })


L1 = ['a','b','c']

L2 = ['m','n','o']

L3 = ['x','y','z']

m1 = df['col_1'].isin(L1) & df['col_1'].shift(-1).isin(L2)
m2 = df['col_1'].isin(L2) & df['col_1'].shift().isin(L1)

df = df[m1 | m2 ].reset_index(drop = True)

intended output:

   col_1
4      n
10     m

Answer 1

you can try:

df[(df['col_1'].isin(L1).shift() & df['col_1'].isin(L2)) & \
    (df['col_1'].isin(L1).shift(-1) & df['col_1'].isin(L2))]

Output:

   col_1
4      n
10     m