Check if a value in one column is in a list in another column using pd.isin()-CodePudding

I have a DataFrame as below

df = pd.DataFrame({
    'x' : range(0,5),
    'y' : [[0,2],[3,4],[2,3],[3,4],[7,9]]
})

I would like to test for each row of x, if the value is in the list specified by column y

df[df.x.isin(df.y)]

so I would end up with:

Not sure why isin() does not work in this case

CodePudding user response：

df.x.isin(df.y) checks for each element x, e.g. 0, is equal to some of the values of df.y, e.g. is 0 equal to [0,2], no, and so on.

With this, you can just do a for loop:

df[ [x in y for x,y in zip(df['x'], df['y'])] ]

CodePudding user response：

Let us try explode with index loc

out = df.loc[df.explode('y').query('x==y').index.unique()]
Out[217]: 
   x       y
0  0  [0, 2]
2  2  [2, 3]
3  3  [3, 4]