How can I filter expressions like ".*_" which contain underscore in R?

Question

Trying to filter phrases in a vector c("phrase\_", "char phrase_char") results only in "phrase\_".

I tried it e.g. with grep and startsWith the "char phrase_char") wasn't found.

Answer 1

If you are talking about vector elements containing specific characters you can use grep().

Example:

test <- c("phrase_", "char phrase_char", "char char2 phrase_","only char char2")
grep("*phrase_*",test)
# [1] 1 2 3
grepl("*phrase_*",test)
# [1]  TRUE  TRUE  TRUE FALSE
test[grep("*phrase_*",test)]
# [1] "phrase_"            "char phrase_char"   "char char2 phrase_"