将一个data.frame的值分配给R中另一个data.frame的特定列？

Question

I would like to replace the first value of column Z of DF2 with the last value of column B of DF1 . I want to make it general, that means, instead of specifying the last row (row number 10) of DF1 column B , is there a way to use end or anything else that would grab the last value of a particular column (in this case column B of DF1 ).

library(tidyverse)

set.seed(1500)

DF1 <- data.frame(A = runif(10,1,5), B = runif(10,5,10))
DF2 <- data.frame(X = runif(10,1,5), Z = runif(10,5,10))

DF2[1,2] <- DF1$B[10, 2]

Answer 1

I believe this can help you:

DF2$Z[1]<-DF1$B[dim(DF1)[1]]

Answer 2

We can use nrow(DF1) . Either extract using the column index or column name with [[ and then with numeric index for first ( 1 ) and last ( nrow ), do the assignment

DF2[[2]][1] <- DF1[[2]][nrow(DF1)]