CODEWITHSUNDEEP
rlistdataframelapply
Johnny Factolive
Johnny Factolive

Reputation: 43

How can I change column names of data.frames within a list with vector of same length in R?

I have a list of length "x" and I want to change a column name of all data.frames within this list using a vector of characters of same length of this list, as described below:

a <- data.frame(rep(1:10), letters[1:10])
b <- data.frame(rep(11:20), letters[11:20])
l <- list(a,b)
nm <- c("letters1:10","letters11:20")

I want something like:

colnames(l[[1]]); colnames(l[[2]])

that gives me

[1] "rep.1.10."     "letters.1.10."
[1] "rep.11.20."     "letters.11.20."

I tried lapply(l, function(x) colnames(x)[2]<-nm) but it returns me a list with nm only and I wanted a list with the original data.frames with updated colnames.

Thank you.

Upvotes: 1

Views: 87

Answers (2)

Onyambu
Onyambu

Reputation: 79188

  Map( function(x,y){colnames(x)[2] <-y;x},l,nm)
 [[1]]
    rep.1.10. letters1:10
 1          1           a
 2          2           b
 3          3           c
 4          4           d
 5          5           e
 6          6           f
 7          7           g
 8          8           h
 9          9           i
 10        10           j

 [[2]]
    rep.11.20. letters11:20
 1          11            k
 2          12            l
 3          13            m
 4          14            n
 5          15            o
 6          16            p
 7          17            q
 8          18            r
 9          19            s
 10         20            t

Upvotes: 0

Dan
Dan

Reputation: 12074

Cludgy, but it seems to work (if I've understood the question).

lapply(as.list(1:2), function(x){colnames(l[[x]])[2] <- nm[x];l[[x]]})

Upvotes: 1

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