Extract all numbers from a single string in R

Question

Let\'s imagine you have a string:

strLine <- \"The transactions (on your account) were as follows: 0 3,000 (500) 0 2.25 (1,200)\"

Is the

Answer 1

library(stringr)
x <- str_extract_all(strLine,"\\(?[0-9,.]+\\)?")[[1]]
> x
[1] "0"       "3,000"   "(500)"   "0"       "2.25"    "(1,200)"

Change the parens to negatives:

x <- gsub("\\((.+)\\)","-\\1",x)
x
[1] "0"      "3,000"  "-500"   "0"      "2.25"   "-1,200"

And then as.numeric() or taRifx::destring to finish up (the next version of destring will support negatives by default so the keep option won't be necessary):

library(taRifx)
destring( x, keep="0-9.-")
[1]    0 3000  -500    0    2.25 -1200

OR:

as.numeric(gsub(",","",x))
[1]     0  3000  -500     0     2.25 -1200

Answer 2

Since this came up in another question, this is an uncrutched stringi solution (vs the stringr crutch):

as.numeric(
  stringi::stri_replace_first_fixed(
    stringi::stri_replace_all_regex(
      unlist(stringi::stri_match_all_regex(
        "The transactions (on your account) were as follows: 0 3,000 (500) 0 2.25 (1,200)", 
        "\\(?[0-9,.]+\\)?"
      )), "\\)$|,", ""
    ),
    "(", "-"
  )
)

Answer 3

What for me worked perfectly when working on single strings in a data frame (One string per row in same column) was the following:

library(taRifx)
DataFrame$Numbers<-as.character(destring(DataFrame$Strings, keep="0-9.-"))

The results are in a new column from the same data frame.

Answer 4

Here's the base R way, for the sake of completeness...

x <- unlist(regmatches(strLine, gregexpr('\\(?[0-9,.]+', strLine)))
x <- as.numeric(gsub('\\(', '-', gsub(',', '', x)))
[1]     0.00  3000.00  -500.00     0.00     2.25 -1200.00