r match filenames in two folders and perform code - r

Question

I have 2 folders with text files: Aba with 90 files and Baa with 50 files. I have a piece of code where I open files with same names from two folders and perform operation.
dna_no= read.table("/home/Documents/Baa/112.txt",skip=1, header=TRUE, sep="\t", fill=FALSE)
sim = read.table("/home/Documents/Data/Aba/112.txt",header=FALSE, sep="\t")
then I want to perform code on contents of files:
Select rows from sim where 1st column of dna_no matches 1st column sim:
sm_dna= sim[which(dna_no[,1]%in%sim[,1]),]
sim_nn17 = cbind(sm_dna[,1],sm_dna[,4:6]
etc.
Now I want to do this in one go for all files in Baa find file with the same name from Aba and do the above operation.
I'm using list.files:
filenames= list.files("/home/Documents/Baa/", full.names=TRUE)
file_sim= list.files("/home/Documents/Data/Aba/",full.names=TRUE)
ldf <- lapply(filenames, function(x) read.table(x,skip=1))
tcf <- lapply(file_sim, function(z) read.table(z,colClasses = c(rep("numeric", 6), rep("NULL", 1)),header=FALSE, sep="\t"))
so now I need to find ldf[i] that is same in tcf [i] , i.e. files with the same names (e.g. 112 file names are all numeric) and I cannot figure out how to do it as list.files seems not to safe files names.
and then perform code for each of the files.
myFun <- function(filenames){
same operation described above for each file:
sm_dna= ..
sim_nn17 =..
...}
I'm not sure how does the code change here as well?
would it be possible do this without loop?
the code works fine for separate files but not for a batch of files in folder.
many thanks for help!

Answer 1

I think you have you two distinct questions here, really.
Find matching list items
Execute some operations on a series of files without a for-loop
The first thing is pretty simple. Here's a reproducible example, but you could use two lists of filenames from calls to list.files or anything here
# here are two random vectors of letters
set.seed(1)
vec1 <- letters[sample(1:26, 5)]
vec2 <- letters[sample(1:26, 15)]
# > vec1
# [1] "g" "j" "n" "u" "e"
# > vec2
# [1] "x" "z" "p" "o" "b" "e" "d" "n" "g" "s" "h" "k" "q" "u" "j"
# here are the matching ones
intersect(vec1, vec2)
# [1] "g" "j" "n" "u" "e"
The second thing is simple too: read in two files of the same name from different locations, perform some operations:
my_func <- function(filename) {
# get files with same name from two dirs
dna_no <- read.table(paste0('/home/Documents/Baa/', filename))
sim <- read.table(paste0('/home/Documents/Data/Aba/', filename))
# do other stuff...
}
Putting these together you can do something like:
filenames <- list.files("/home/Documents/Baa/")
file_sim <- list.files("/home/Documents/Data/Aba/")
lapply(intersect(filenames, file_sim), my_func)