如何删除R中字符串中的一些字符

Question

I analyse some gene id. these Ids similar as follow:

"ENSG00000189001.9" "ENSG00000179152.17" "ENSG00000131374.13"

1- I would like to remove '.' and every character after that such as follow:

"ENSG00000189001" "ENSG00000179152" "ENSG00000131374"

2-After step1, I would like to remove "" from my string such as below:

ENSG00000189001 ENSG00000179152 ENSG00000131374

Answer 1

You can do this using gsub

GID = c("ENSG00000189001.9", "ENSG00000179152.17", "ENSG00000131374.13")
GID2 = gsub("\\..*", "", GID)
cat(GID2, "\n")
ENSG00000189001 ENSG00000179152 ENSG00000131374 

Note that if you just type GID2, you will still see the quotes. That is just how R indicates that these are strings. Using cat shows only the string contents

A little detail about the regular expression:
\\\\. matches the first period found in each string.
.* matches everything after that.
gsub will replace the matched part (period and everything after) with "", ie the empty string.

Answer 2

Here are a few fun, out of the ordinary ways to get the desired result.

scan(text=GID, what="", comment.char=".")
# Read 3 items
# [1] "ENSG00000189001" "ENSG00000179152" "ENSG00000131374"
dirname(chartr(".", "/", GID))
# [1] "ENSG00000189001" "ENSG00000179152" "ENSG00000131374"
read.table(text=GID, sep=".", stringsAsFactors=FALSE)$V1
# [1] "ENSG00000189001" "ENSG00000179152" "ENSG00000131374"
stringi::stri_split_fixed(GID, ".", simplify=TRUE)[,1]
# [1] "ENSG00000189001" "ENSG00000179152" "ENSG00000131374"

Data:

GID <- c("ENSG00000189001.9", "ENSG00000179152.17", "ENSG00000131374.13")