select data in pandas dataframe based on column

Question

Let's say I have a pandas dataframe df1 and array of values a1

df1
col1 |col2 
A    |123
B    |321
C    |2323
D    |3232

a1
[A,B,A,D]

I'd like to return a dataframe df2 with len(a1) rows.

df2
    col1 |col2 
    A    |123
    B    |321
    A    |123
    D    |3232

I've been trying using iloc, loc but I can't find a suitable solution...

edit: I've tried using

len(df1[df1['col1'].isin(a1)])

but I think this solution only returns unique rows and it doesnt duplicate them like I need it to.

user3483203 · Accepted Answer · 2018-07-20 08:28:02Z

2

You need to set_index before you can use loc with your list of values:

a1 = ['A', 'B', 'A', 'D']
df.set_index('col1').loc[a1]

      col2
col1
A      123
B      321
A      123
D     3232

answered Jul 20, 2018 at 8:28

user3483203

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1 Comment

Kristjan Over a year ago

it works! I'm not exactly sure how set_index works, but it works.... I found a solution using isin but that one doesnt include duplicated rows. Thanks!

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