How to match a string and white space in R

Question

I have a dataframe with columns having values like:

"Average 18.24" "Error 23.34". My objective is to replace the text and following space from these. in R. Can any body help me with a regex pattern to do this?

I am able to successfully do this using the [A-Z]. But i am not able to combine the white space. [A-Z][[:space:]] no luck. Your help is appreciated.

As you can see, you failed because `[A-Z]` does not match lowercase letters, and `[A-Z]` without a `+` or `*` matches 1 symbol. With `+` after it, it matches 1 or more letters, with `*` it matches 0 or more. — Wiktor Stribiżew, Jul 15 '16 at 09:38
Glad [my solution](https://stackoverflow.com/a/38392533/3832970) helped, please consider accepting. — Wiktor Stribiżew, Mar 07 '21 at 13:29

score 11 · Answer 1 · answered Jul 15 '16 at 09:26

You can use a quantifier and add a-z to the pattern (and the ^ anchor)

You can use

"^\\S+\\s+"
"^[a-zA-Z]+[[:space:]]+"

See regex demo

R demo:

> b <- c("Average 18.24", "Error 23.34")
> sub("^[A-Za-z]+[[:space:]]+", "", b)
> ## or sub("^\\S+\\s+", "", b)
[1] "18.24" "23.34"

Details:

^ - start of string
[A-Za-z]+ - one or more letters (replace with \\S+ to match 1 or more non-whitespaces)
[[:space:]]+ - 1+ whitespaces (or \\s+ will match 1 or more whitespaces)

score 11 · Accepted Answer · edited Jun 20 '20 at 09:12

11

We can use sub. Use the pattern \\D+ to match all non-numeric characters and then use '' in the replacement to remove those.

sub("\\D+", '', v2)
#[1] "18.24" "23.34"

Or match one or more word characters followed by one or more space and replace with ''.

 sub("\\w+\\s+", "", v2)
 #[1] "18.24" "23.34"

Or if we are using stringr

library(stringr)
word(v2, 2)
#[1] "18.24" "23.34"

data

v2 <- c("Average 18.24" ,"Error 23.34")

edited Jun 20 '20 at 09:12

Community

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answered Jul 15 '16 at 09:26

akrun

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love the `word()` sol ... :) – Sotos Jul 15 '16 at 09:54
Thank you for explanation. It helped me to fix my error – duvvurum Aug 02 '16 at 06:21

How to match a string and white space in R

2 Answers2

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