Hello,
With the new data, here are two ways.
The first with a for loop. I find it simple and readable.
for(b in unique(B[,1])){
A[which(A[,1] == b), 2] <- B[which(B[,1] == b), 2]
}
na <- is.na(A[,2])
A[!na, 2]
sum(!na) # [1] 216
sum(A[,1] %in% B[,1]) # [1] 216
# Another way,
; Mohammad Tanvir Ahamed ; Avi
Gross ; Richard M. Heiberger
Subject: Re: [R] conditional replacement of elements of matrix with another
matrix column
I thank you all. But the code doesn't work on my different dataset where A
and B have different column lengths. For example,
> dput(A)
str
: Wednesday, September 1, 2021 6:00 PM
To: r-help@r-project.org; Mohammad Tanvir Ahamed ; Avi
Gross ; Richard M. Heiberger
Subject: Re: [R] conditional replacement of elements of matrix with another
matrix column
I thank you all. But the code doesn't work on my different dataset where A
I thank you all. But the code doesn't work on my different dataset where A and
B have different column lengths. For example,
> dput(A)
structure(c(17897, 17897, 17897, 17897, 17897, 17897, 17897,
17897, 17897, 17897, 17897, 17897, 17897, 17897, 17897, 17897,
17897, 17897, 17897, 17897, 17897, 178
C1 <- A
C1[,2][which(B[,1]%in%A[,1])] <- B[,2][which(B[,1]%in%A[,1])]
Regards.
Tanvir Ahamed
On Wednesday, 1 September 2021, 11:00:16 pm GMT+2, Eliza Botto
wrote:
deaR useRs,
I have the matrix "A" and matrix "B" and I want the matrix "C". Is there a way
of doing it?
Seems trivial enough Elizabeth, either using a matrix or data.frame.
R is vectorized mostly so A[,1] notation selects a column all at once. Your
condition is thus:
A[,1] == B[,1]
After using your sample data to initialize an A and a B, I get this:
> A[,1] == B[,1]
[1] FALSE FALSE FALSE TRUE T
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