Merging a list of vectors with a list of dataframes in R

Question

I have a list of dataframes lsD and a list of vectors lsV . The length of the vectors is identical to the numbers of rows in the dataframes (in the toy example = 5).

I would like to add the vectors as an additional column to each dataframe. I got it to work with a for loop, but my general question is: how can iterate through two lists by name without for ? Is there a lapply way to do this?

Here is a toy example and my solution using the for loop:

lsV <- list(x = sample(LETTERS[1:5], 5,replace=T), 
            y = sample(LETTERS[1:5], 5, replace=T), 
            z=sample(LETTERS[1:5], 5, replace=T))

lsD <- list(x = data.frame(matrix(sample(LETTERS[1:5], 20,replace=T), ncol=4)), 
        y = data.frame(matrix(sample(LETTERS[1:5], 20,replace=T), ncol=4)),
        z =  data.frame(matrix(sample(LETTERS[1:5], 20,replace=T), ncol=4)))

for (i in 1:length(lsV)) {lsD[[i]]<-cbind(lsD[[i]], lsV[[i]])}

Any ideas? I tried with the following, but of course it didn't work. Thanks!

lapply(names(lsD), function(X) {lsD$X<-cbind(lsD$X, lsV$X)})

Answer 1

The Map function would be useful here

 Map(cbind, lsD, Z=lsV)

Both Map and mapply are apply-style functions that accept multiple parameters and iterate over them simultaneously.

And

lapply(names(lsD), function(X) {lsD$X<-cbind(lsD$X, lsV$X)})

will never work because you can't use variable names with the '$' operator. You can use

lapply(names(lsD), function(X) {lsD[[X]]<-cbind(lsD[[X]], lsV[[X]])})