mirror of
https://github.com/agdamsbo/stRoke.git
synced 2024-11-22 04:50:23 +01:00
38 lines
1.3 KiB
R
38 lines
1.3 KiB
R
#' Extract string based on regex pattern
|
|
#'
|
|
#' Use base::strsplit to
|
|
#' @param d vector of character strings
|
|
#' @param pattern regex pattern to match
|
|
#'
|
|
#' @return vector of character strings
|
|
#' @export
|
|
#'
|
|
#' @examples
|
|
#' ls <- do.call(c,lapply(sample(4:8,20,TRUE),function(i){
|
|
#' paste(sample(letters,i,TRUE),collapse = "")}))
|
|
#' ds <- do.call(c,lapply(1:20,function(i){
|
|
#' paste(sample(ls,1),i,sample(ls,1),"23",sep = "_")}))
|
|
#' str_extract(ds,"([0-9]+)")
|
|
str_extract <- function(d,pattern){
|
|
if (!is.vector(d)) stop("Please provide a vector")
|
|
|
|
## Drawing on the solution in REDCapCAST::strsplitx to split around pattern
|
|
nl <- strsplit(gsub("~~", "~", # Removes double ~
|
|
gsub("^~", "", # Removes leading ~
|
|
gsub(
|
|
# Splits and inserts ~ at all delimiters
|
|
paste0("(", pattern, ")"), "~\\1~", d
|
|
))), "~")
|
|
|
|
## Reusing the pattern, to sub with "" and match on length 0 to index the
|
|
## element containing the pattern. Only first occurance included.
|
|
indx <- lapply(nl,function(i){
|
|
match(0,nchar(sub(pattern,"",i)))
|
|
})
|
|
|
|
## Using lapply to subsset the given index for each element in list
|
|
do.call(c,lapply(seq_along(nl), function(i){
|
|
nl[[i]][indx[[i]]]
|
|
} ))
|
|
}
|