CODEWITHSUNDEEP
rdataframe
user3067818
user3067818

Reputation: 7

Matching and call data from 2 data frames in R

I have two data frames, A and B.
First I want to match two columns from B(id and type) to A.
If they have the same elements then I want to call all the other information in A to new dataframe C.

For example

A

id  type  info1  info2  info3  info4   
a   t1    *      ~       ~      ~       
b   t5    *      ~       ~      ~       
c   t3    *      ~       ~      ~       
a   t2    *      ~       ~      ~       
b   t3    *      ~       ~      ~

B

id   %    type  
a    .2   t1  
b    .15  t2  
c    .1   t3

a and c have both same types in A and B
So I want to create a new data frame C with all the other columns which a and c have in A,

id type  info1  info2  info3  info4  
A  t1     *       ~      ~      ~  
C  t3     *       ~      ~      ~

I tried
C = merge(A, C, by = c("type", "id"))

but I think it shows all the type and id which are both in A and B.

Upvotes: 0

Views: 63

Answers (1)

jlhoward
jlhoward

Reputation: 59425

Looks like you want to extract from A only those rows where id and type match in B. You can use merge for this:

C <- merge(A,B[,c("id","type")])
C
#   id type info1 info2 info3 info4
# 1  a   t1     *     ~     ~     ~
# 2  c   t3     *     ~     ~     ~

You don't need by=... in this because the only columns in the second argument are id and type, and merge works on all common columns by default.

Upvotes: 1

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