Replacing a numeric value in a string using R

Question

I want to replace DM*13:01:01:02 with DM*13:01:01:01. However my script also changes DM*11:01:01:01, DM*03:01:01:01, DM*01:01:01:01 to DM*13:01:01:01. I do not want these to be changed

The script I use:

> papST$DM_c1 <-gsub("[DM*]\\d[13][:]\\d[01][:]\\d[01][:]\\d[02]", "*13:01:01:01", papST$DM_o1, perl = TRUE)

You should try entering your regex into a helper tool like regex101.com. Your regex contains a lot of things that don't make sense to me, especially if you are basically trying to match a single fixed string. — Marius
– Marius, Commented Jun 2, 2017 at 0:04
\\d means any digit. [xy] matches any character x or y. So \\d[13] matches 01,03,11,13,21,23.... and so on. Why not just gsub("DM*13:01:01:02", "DM*13:01:01:01", papST$DM_o1, fixed=TRUE) ? — thelatemail
– thelatemail, Commented Jun 2, 2017 at 0:05
Thank you, my problem was I tried to over complicate a relatively simple substitution. — Mona
– Mona, Commented Jun 2, 2017 at 0:37

Marius · Accepted Answer · 2017-06-02 00:13:31Z

1

Based on the examples you have given, you don't really need to use any fancy regex features to do the specific replacement you have mentioned. The only thing you need to include in your pattern is a backslash so that * doesn't get treated as a special character:

x = c("DM*13:01:01:02", "DM*11:01:01:01", "DM*03:01:01:01", "DM*01:01:01:01")
gsub("DM\\*13:01:01:02", "DM*13:01:01:01", x)

If there are more values that need replacing, like you want to replace all values ending in 02, then you may need to bring in some of the "pattern matching" features in regular expressions, but it's important not to overcomplicate things.

For reference, to replace all 02s at the end of your strings, you could use a simple regex that uses $, which matches at the end of a string:

gsub("02$", "01", x)

answered Jun 2, 2017 at 0:13

Marius

60.6k16 gold badges115 silver badges108 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Mona Over a year ago

Great a simple script works, I will remember this for the future. Thank you!

Collectives™ on Stack Overflow

Replacing a numeric value in a string using R

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related