从字符串中提取特定值

Question

Suppose I have a list of string:

distance <- c("CHI #12 DEBRINCAT(1), Snap, Off. Zone, 18 ft.Assists: #88 KANE(2); #56 GUSTAFSSON(1)", "TOR ONGOAL - #44 RIELLY, Backhand, Off. Zone, 77 ft.")

Now I hope to get a string vector that contains only the parts that contains the distance, that is, substring = c ("18 ft", "77 ft").

Is there a convenient way in R to do this?

Answer 1

Using str_extract to match one or more digits followed by zero or more spaces ( \\s* ) and the substring 'ft'

library(stringr)
str_extract(distance, "\\d+\\s*ft")
#[1] "18 ft" "77 ft"

Answer 2

Alternatives:

regmatches(distance, gregexpr("\\b[0-9]+\\s*ft", distance, perl = TRUE))
# [[1]]
# [1] "18 ft"
# [[2]]
# [1] "77 ft"

strcapture("\\b([0-9]+\\s*ft)", distance, list(dist = ""))
#    dist
# 1 18 ft
# 2 77 ft

Though they're all just doing the same thing with slightly different interfaces.

Answer 3

Try gsub

> gsub(".*?(\\d+\\s+ft).*", "\\1", distance)
[1] "18 ft" "77 ft"