Removing patterns in R

Question

I have a character string that looks like below and I want to delete lines that doesn't have any value after '_'. How do I do that in R?

 [985] "Pclo_"                "P2yr13_ S329"         "Basp1_ S131"         
 [988] "Stk39_ S405"          "Srrm2_ S351"          "Grin2b_ S930"        
 [991] "Matr3_ S604"          "Map1b_ S1781"         "Crmp1_"              
 [994] "Elmo1_"               "Pcdhgc5_"             "Sp4_"                
 [997] "Pbrm1_"               "Pphln1_"              "Gnl1_ S33"           
[1000] "Kiaa1456_"

Does this answer your question? [How to determine if a string "ends with" another string in R?](https://stackoverflow.com/questions/26188663/how-to-determine-if-a-string-ends-with-another-string-in-r) — slava-kohut, Jul 09 '20 at 23:13

akrun · Accepted Answer · 2020-07-09T23:21:07.447

1

We can use grep

grep("_$", v1, invert = TRUE, value = TRUE)

Or endsWith

v1[!endsWith(v1, "_")]

edited Jul 09 '20 at 23:21

answered Jul 09 '20 at 22:54

akrun

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score 0 · Answer 2 · answered Jul 10 '20 at 01:58

We can use substring to get the last character in the vector and select if it is not "_".

x <- c("Pclo_","P2yr13_ S329","Basp1_ S131")
x[substring(x, nchar(x)) != '_']
#[1] "P2yr13_ S329" "Basp1_ S131"

Last character can be extracted using regex as well with sub :

x[sub('.*(.)$', '\\1', x) != '_']

Removing patterns in R

2 Answers2