Searching values from dataframe1 to dataframe2 in pandas

Question

let's say I have a my source dataframe:

A B C
a 1 string1
b 1 string1
b 4 string2
c 2 string4
d 2 string2

and I have my input dataframe

A B C
a null string1
b null string2

How am I able to cross check values from my input dataframe to my source I want to find which rows in my source dataframe that has values from my input dataframe. I tried isin but its returning a dataframe full of nan values

Result would be a df:

A B C
a 1 string1 #Ref to a null string1
b 1 string1 #Ref to b null string2
b 4 string2 #Ref to b null string2
d 2 string2 #Ref to b null string2

What values are you checking from both? I don't quite understand how you got your resulting df. — Joe Patten, Jul 03 '19 at 00:27

score 0 · Accepted Answer · answered Jul 03 '19 at 00:38

0

It looks like you are filtering your source df keeping only rows that have values in column C that are in your input df column C. If that is the case, you can use input_df['C'].unique() to give you an array of the unique values in column C in your input df, and you can use isin to filter your source df:

source_df[source_df['C'].isin(input_df['C'].unique())]

which gives an output of:

    A   B   C
0   a   1   string1
1   b   1   string1
2   b   4   string2
4   d   2   string2

answered Jul 03 '19 at 00:38

Joe Patten

1,574
1
6
15

how do we do this for all columns? – dekt Jul 03 '19 at 01:22
You could merge on the columns you wish to match. One of the suggested links goes into depth on merging. – Joe Patten Jul 03 '19 at 01:32

Searching values from dataframe1 to dataframe2 in pandas

1 Answers1