Using Regex to extract from second period to end of a string - regex

Question

I'm using gsub in R to extract parts of a string. Everything before the first period is the building. Everything between the first and second period is the name of a piece of equipment. Everything after the second period is the point name. I've managed to figure out how to get the building and equipment, but haven't figured out the point. See below (obviously the line with "point" is incorrect):
library(tidyverse)
df <- data_frame(
var = c("buildA.equipA.point", "buildA.equipA.another.point",
"buildA.equipA.yet.another.point")
)
df2 <- df %>%
mutate(
building = gsub("(^[^.]*)(.*$)", "\\1", var),
equip = gsub("^[^.]*.([^.]+).*", "\\1", var),
point = gsub("^[^.].*", "\\1", var)
)

Answer 1

You may use tidyr::extract here with the regex like
^([^.]+)\.([^.]+)\.(.+)$
See the regex demo.
Details
^ - start of string
([^.]+) - Group 1 (Column "building"): one or more chars other than a dot
\. - a dot
([^.]+) - Group 2 (Column "equip"): one or more chars other than a dot
\. - a dot
(.+) - Group 3 (Column "point"): any 1 or more chars other than line break chars, as many as possible
$ - end of string (not necessary here though).
R demo:
library(tidyverse)
df <- data_frame(
var = c("buildA.equipA.point", "buildA.equipA.another.point",
"buildA.equipA.yet.another.point")
)
df2 <- df %>% extract(var, c("Building", "equip", "point"), "^([^.]+)\\.([^.]+)\\.(.+)$")
df2
# A tibble: 3 x 3
Building equip point
<chr> <chr> <chr>
1 buildA equipA point
2 buildA equipA another.point
3 buildA equipA yet.another.point

Answer 2

You can do something like ^(?:.*?\.){2}(.*) this will match the beginning of the line with ^, then it will match 0 or more characters followed by a . twice in a non-capturing group. After that there only rests the part you're interested in, which we put in a capturing group.
I'm aware this question is not about javascript, but here you can see a working version.
const regex = /^(?:.*?\.){2}(.*)$/gm;
const str = `buildA.equipA.point
buildA.equipA.another.point
buildA.equipA.yet.another.point`;
let m;
while ((m = regex.exec(str)) !== null) {
// This is necessary to avoid infinite loops with zero-width matches
if (m.index === regex.lastIndex) {
regex.lastIndex++;
}
console.log(m[1]);
}