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Multiply columns in a data frame by vector

What I want to do is multiply all the values ​​in column 1 of data.frame by the first element in the vector, and then multiply all the values ​​in column 2 by the 2nd element in the vector, etc.

c1 <- c(1,2,3) c2 <- c(4,5,6) c3 <- c(7,8,9) d1 <- data.frame(c1,c2,c3) c1 c2 c3 1 1 4 7 2 2 5 8 3 3 6 9 v1 <- c(1,2,3)

So the result is this:

  c1 c2 c3 1 1 8 21 2 2 10 24 3 3 12 27

I can do this one column at a time, but what if I have 100 columns? I want to be able to do this programmatically.

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3 answers

Transportation work dataframe.

 c1 <- c(1,2,3) c2 <- c(4,5,6) c3 <- c(7,8,9) d1 <- data.frame(c1,c2,c3) v1 <- c(1,2,3) t(t(d1)*v1) # c1 c2 c3 #[1,] 1 8 21 #[2,] 2 10 24 #[3,] 3 12 27

EDIT: if all columns are not numeric, you can do the following

 c1 <- c(1,2,3) c2 <- c(4,5,6) c3 <- c(7,8,9) d1 <- data.frame(c1,c2,c3) # Adding a column of characters for demonstration d1$c4 <- c("rr", "t", "s") v1 <- c(1,2,3) #Choosing only numeric columns index <- which(sapply(d1, is.numeric) == TRUE) d1_mat <- as.matrix(d1[,index]) d1[,index] <- t(t(d1_mat)*v1) d1 # c1 c2 c3 c4 #1 1 8 21 rr #2 2 10 24 t #3 3 12 27 s
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Or just diagonalize the vector so that each row entry is multiplied by the corresponding element in v1:

 c1 <- c(1,2,3) c2 <- c(4,5,6) c3 <- c(7,8,9) d1 <- as.matrix(cbind(c1,c2,c3)) v1 <- c(1,2,3) d1%*%diag(v1) [,1] [,2] [,3] [1,] 1 8 21 [2,] 2 10 24 [3,] 3 12 27
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We can also replicate the vector to make the lengths equal, and then multiply

 d1*v1[col(d1)] # c1 c2 c3 #1 1 8 21 #2 2 10 24 #3 3 12 27

Or use sweep

 sweep(d1, 2, v1, FUN="*")

Or using mapply to multiply the corresponding columns of "data.frame" and the elements of "vector"

 mapply(`*`, d1, v1)
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