## Import files:
temp = list.files(pattern="*.csv")  #Filenames from working directory
for (i in 1:length(temp)) {
    assign(temp[i], read.delim(temp[i],sep=";", header = T, nrows = 6)) #Clean data to include only RGB
}

allvars <- ls(all.names = T) #List all variables

getClasses <- function(variable) {  #Find RGB classes and name
    red <- variable$R[3:5]
    green <- variable$G[3:5]
    blue <- variable$B[3:5]
    classes <- data.frame(red, green, blue)
    print(classes)
}

#This is where the problem happens:
for (i in 1:length(allvars)) {
    assign(allvars[i], getClasses(allvars[i]))  #Apply getClasses function to current variable and store new data
}
#Error: $ operator is invalid for atomic vectors