How to change multiple variable names in R?

Question

I am new to R

I am trying to create a variable list with variables containing the log of some other variables. I managed to create the list, but I don't know how to rename each variable. Moreover, I don't know how to make these variables be a part of my dataset. Here is what I do:

Imagine somedata is a csv file of the form:

v1,  v2,  v3, ...,  vn
1, 4, 6,    ...,  1
...

Then here is my script

##################
## Import Data
###################
lights <- read.csv("somedata.csv")  

##################
## Variable Lists
###################
 lights.varlist1 <- subset(lights, select=c(v1,v2,...,vJ))

 ###########
 ## Logs
 ###########

 lights.logsvarlist1=apply(lights.varlist1, 2, function(y) log(y))

This part seems to be working just fine as the results of print(lights.logsvarlist1)[1,] make sense

To change the names of the variables I do:

for (i in 1:length(lights.logsvarlist1[1,]) {
    name <-paste("l", names(lights.varlist1)[i], separator="")
    names(lights.logsvarlist1)[i]=name
}

I have now two problems.

1. When I print(lights.logsvarlist1[1,], the names don't seem to have changed. I still have my old variable names as headers.

2. When I print(names(lights)), my newly created variables don't seem to be part of the dataset (they are not in the list).

What am I doing wrong? I am very new to R and I really want to continue, I'd appreciate any help.

Answer 1

DF <- data.frame(a=1:3, v1=4:6, v2=7:9, v3=10:12)

sub <- c("v1", "v2", "v3")
DF[, paste0("l", sub)] <- lapply(DF[, sub], log)

#   a v1 v2 v3      lv1      lv2      lv3
# 1 1  4  7 10 1.386294 1.945910 2.302585
# 2 2  5  8 11 1.609438 2.079442 2.397895
# 3 3  6  9 12 1.791759 2.197225 2.484907

Answer 2

This works for me and avoids the for loop

data = as.data.frame(matrix(abs(rnorm(100)), 10))
ldata = log(data)
names(ldata) = paste('log', names(ldata), sep = '')

Some other tips

apply(lights.varlist1, 2, function(y) log(y))

Can be replaced by

apply(lights.varlist1, 2, log)

As log is a function or simply

log(lights.varlist1)

Instead of the following

for (i in 1:length(lights.logsvarlist1[1,])

use

ncol(lights.logsvarlist1)

Your new variables aren't in the lights data frame. They are in a data frame called

lights.logsvarlist1

To put them in the data frame use merge or cbind. Type ?merge etc