CODEWITHSUNDEEP
r
noriega
noriega

Reputation: 448

Get a list of files with exceptions using pattern

Using only the pattern argument from the list.files() function how could I get a file list excluding some files with similar pattern?

Let's say I have this files in my working directory:

med_t_1_1.csv, 01_t_1_1.csv, 02_t_1_1.csv, 03_t_1_1.csv,
med_t_2_1.csv, 01_t_2_1.csv, 02_t_2_1.csv, 03_t_2_1.csv

I want to get the files with the pattern t_1_1 but the one that starts with med:

01_t_1_1.csv, 02_t_1_1.csv, 03_t_1_1.csv

Upvotes: 1

Views: 281

Answers (2)

CPak
CPak

Reputation: 13591

You can use regular expression

S[grepl("(?<!med_)t_1_1", S, perl=TRUE)]
# "01_t_1_1.csv" "02_t_1_1.csv" "03_t_1_1.csv"

Explanation of regex

(?<!med_) = (?< looks behind, ! does not match, med_ is the string

Look behind for string that does not match the string med_

t_1_1 = t_1_1 is string

Look for any string that matches t_1_1

**Other example

S1 <- c("med_t_1_1.csv", "S_t_1_1.csv", "04_t_1_1.csv")
S1[grepl("(?<!med_)t_1_1", S1, perl=TRUE)]
# "S_t_1_1.csv"  "04_t_1_1.csv"

Upvotes: 2

Nate
Nate

Reputation: 10671

file_chrs <- c("med_t_1_1.csv", "01_t_1_1.csv", "02_t_1_1.csv", "03_t_1_1.csv",
               "med_t_2_1.csv", "01_t_2_1.csv", "02_t_2_1.csv", "03_t_2_1.csv")

file_chrs[grepl("\\d_t_1_1", file_chrs)] # \\d matches and digit [0-9]

# console
[1] "01_t_1_1.csv" "02_t_1_1.csv" "03_t_1_1.csv"

# so in your working directory
list.files( pattern = "\\d_t_1_1" )

Upvotes: 2

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