CODEWITHSUNDEEP
r
Ananta
Ananta

Reputation: 3711

columnwise sum matching values to another column

Seems, I am missing some link here. I have data frame

df<-data.frame(w=sample(1:3,10, replace=T), x=sample(1:3,10, replace=T), y=sample(1:3,10, replace=T), z=sample(1:3,10, replace=T))

> df
   w x y z
1  3 1 1 3
2  2 1 1 3
3  1 3 2 2
4  3 1 3 1
5  2 2 1 1
6  1 2 2 3
7  1 2 2 2
8  2 2 2 3
9  1 3 3 3
10 2 2 1 1

I want to get the number of rows of each column which matches to 1st column. 

sum(df$w==df$x)
[1] 3

 sum(df$w==df$y)
[1] 2
 sum(df$w==df$z)
[1] 1

I know using apply, I can do rowwise or colwise operations. 

 apply(df,2,length)
 w  x  y  z 
10 10 10 10

How do I combine these two functions?

Upvotes: 3

Views: 86

Answers (1)

David Arenburg
David Arenburg

Reputation: 92292

Try colSums

colSums(df[-1] == df[, 1])
# x y z 
# 3 2 1

Or if you into *apply loops could try 

vapply(df[-1], function(x) sum(x == df[, 1]), double(1))

Upvotes: 4

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