CODEWITHSUNDEEP
r
polarsandwich
polarsandwich

Reputation: 135

Listing files according to complex pattern

I've got a list of files that I want to import into R. They look like this:

 > dput(asia)
   "chin074.csv", "indi001.csv", "indi001e.csv", "indi001l.csv", 
   "indi001n.csv", "indi001x.csv", "indi002.csv", "indi002e.csv", ...

I want to import only those files that do not have a letter after the main name. So, I want to import chin074.csv and indi001.csv but not indi001e.csv or indi001l.csv, which have letters e and l after the main title.

I know I can use some variation of grep to do this, but I can't figure out how. So something like this:

asia<-grep(list.files(path="./asia/"), pattern='?', inv=T, value=T) 
asia_new<- lapply(asia, read.csv)

How do I do this?

Upvotes: 2

Views: 42

Answers (2)

akrun
akrun

Reputation: 887901

We can also do

grep("[a-z]+[0-9]+\\.csv", asia, value = TRUE)
#[1] "chin074.csv" "indi001.csv" "indi002.csv"

data

asia <- c("chin074.csv", "indi001.csv", "indi001e.csv", "indi001l.csv", 
      "indi001n.csv", "indi001x.csv", "indi002.csv", "indi002e.csv")

Upvotes: 1

Ronak Shah
Ronak Shah

Reputation: 389275

You can use the pattern : 

asia <- grep('[a-z]+\\d+\\.csv', asia, value = TRUE)
#[1] "chin074.csv" "indi001.csv" "indi002.csv"

We select the files which has one or more lower case letters (a-z), followed by one or more numbers, followed by .csv.

data

asia <- c("chin074.csv", "indi001.csv", "indi001e.csv", "indi001l.csv", 
          "indi001n.csv", "indi001x.csv", "indi002.csv", "indi002e.csv")

Upvotes: 2

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