CODEWITHSUNDEEP
arraysrloopsimport
user2113499
user2113499

Reputation: 1021

Importing files into array with R

I have multiple csv files that are within one folder. Each csv file contains a table of 200 rows and 200 columns. I can bring in each file individually and display it as an matrix. I can also do a dir and list each file in the folder where they are located. What I need to do is bring in each file, open them and then combine them into an array. When I do this though I get a warning that there is no such file.

my code for this is

x <- dir(path=" ", pattern = ".csv")
num <- array(0,dim=c(200,200,length(x)))
for(i in 1:length(x)){
  temp <- read.csv(x[i], skip=1)
  temp2 <- temp[,2]
  num[,i]<-temp2

}

This gives me the warning

Error in file(file, "rt") : cannot open the connection
In addition: Warning message:
In file(file, "rt") :
  cannot open file 'test_1.csv': No such file or directory

Again, when I am working with individual files I can import them just fine and and list them and open them as a matrix. Why am I getting this warning? Why is R able to find my file when I do one at a time but not for multiple at a time?

Upvotes: 3

Views: 2046

Answers (1)

tepedizzle
tepedizzle

Reputation: 468

First are you sure you are reading the list of files into the variable x properly. I think there are some issues with your for loop. Also are you sure you are in the same directory as those files? In the dir command you enter " " for the path variable, I am not sure what that means. Try this

> x <- dir(pattern = ".csv")
> num <- array(0,dim=c(200,200,length(x))) # in my case `length(x)` is 9.
> m <- matrix(rnorm(200*200),nrow=200,ncol=200) # generate some 200x200 matrix
> for(i in 1:length(x)){
    num[,,i] <- m # notice its num[,,i] and not num[,i]
}
> num[1:4,1:4,9]
           [,1]        [,2]       [,3]       [,4]
[1,] -1.5674073  0.05364477  0.8367233  1.7995047
[2,] -0.8613244  1.00400787 -0.2464169 -1.2897856
[3,] -0.7907845 -1.40617992  1.0596680 -0.5270983
[4,] -0.5206049  0.66253519  1.6820722  1.2017410

Upvotes: 2

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