Extracting RGB values of multiple images in R

[Danah]

Hello,
I'm very new to R, and I'm trying to load multiple images in R and extract the RGB values of each image (as matrix). I managed to do it for single image at a time, but I need to do it for multiple images at once.
I tried the below code but it only saves the RGB matrices of the last image in the folder.
Can someone help me find a way to keep the values of all images?

Thank you!

filenames <- list.files(path="/Users/danah........")
for(i in filenames){
filepath <- file.path("/Users/dana..........", paste(i))
im <- load.image(filepath)
Red <- im[,,1]
Green <- im[,,2]
Blue <- im[,,3]
}

[FJCC]

Your code overwrites the Red, Green, and Blue vectors on every iteration. One solution is to store the information from the files in lists.

filenames <- list.files(path="/Users/danah........")
Red <- vector(mode = "list", length = length(filenames))
Green <- vector(mode = "list", length = length(filenames))
Blue <- vector(mode = "list", length = length(filenames))
for(i in filenames){
  filepath <- file.path("/Users/dana..........", paste(i))
  im <- load.image(filepath)
  Red[[i]] <- im[,,1]
  Green[[i]] <- im[,,2]
  Blue[[i]] <- im[,,3]
}

[nirgrahamuk]

I would prefer a list based approach

library(tidyverse)
library(imager)

filenames <- list.files(path="/Users/danah........")

results <- map(filenames,\(x_){
  
  im <- load.image(x_)

  list(Red  = im[,,1],
       Green= im[,,2],
       Blue = im[,,3])
}) |> set_names(filenames)

[Danah]

Great! I was trying a similar approach but I was using single square brackets and it kept giving me an error message.
Thank you so much!

[Danah]

For the list approach, I think it might be a good idea but it keeps giving me an error message saying file not found (attached). I'm not sure what the issue is.

[nirgrahamuk]

ok yes, my code did assume everything was in your wd, but we can make the relative paths explicit.

library(tidyverse)
library(imager)

rel_path <- "/Users/danah........"
(filenames <- list.files(path = rel_path))

results <- map(filenames,\(x_){
  
  im <- load.image(file.path(rel_path,
                             x_))
  
  list(Red  = im[,,1],
       Green= im[,,2],
       Blue = im[,,3])
}) |> set_names(filenames)

[Danah]

works perfectly, thank you!