How to select rows having values equal to a unqiue value in another dataframe column?

Question

I have two dataframes as follows:

df1:

df2:

Now I want to retain rows in df1, such that value of column "col1" in df1, is present in df2 "col2"

Is there a simple straightforward way to achieve it in Python?

Currently, I am doing it in a brute way with 2 nested for loops, but it is computationally intensive.

zabop · Accepted Answer · 2021-09-29 20:27:36Z

2

You can do:

df1[df1.col1.isin(df2.col1)]

Example:

Create df1:

data = {'col1': ['a','b','c','d'],
        'col2': [1,2,3,4]}
df1 = pd.DataFrame(data)

and df2:

df2 = pd.DataFrame({'col1': ['a','d']})

then df1[df1.col1.isin(df2.col1)] will be:

  col1  col2
0    a     1
3    d     4

answered Sep 29, 2021 at 20:25

zabop

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2 Comments

what is df in here?

Sorry, typo, edited my answer.