pandas new column counting id's existence in other dataframe [duplicate]

This is my initial dataframe dfA :

idA	data
1	row
2	data
3	data

dataframe dfB

idC	idA
1	1
2	1
3	3
4	3
5	3
6	3

I am trying to count every id existence of dfA in dfB , and add to new column like this:

idA	data	count
1	row	2
2	data	0
3	data	4

how can i do this plz

https://stackoverflow.com/questions/67260701/pandas-new-column-counting-ids-existence-in-other-dataframe April 26, 2021 at 12:03PM