Insert a character at a specific location in a string

by

You can do this with regular expressions and gsub.

gsub('^([a-z]{3})([a-z]+)$', '\\1d\\2', old)
# [1] "abcdefg"

If you want to do this dynamically, you can create the expressions using paste:

letter <- 'd'
lhs <- paste0('^([a-z]{', n-1, '})([a-z]+)$')
rhs <- paste0('\\1', letter, '\\2')
gsub(lhs, rhs, old)
# [1] "abcdefg"

as per DWin’s comment,you may want this to be more general.

gsub('^(.{3})(.*)$', '\\1d\\2', old)

This way any three characters will match rather than only lower case. DWin also suggests using sub instead of gsub. This way you don’t have to worry about the ^ as much since sub will only match the first instance. But I like to be explicit in regular expressions and only move to more general ones as I understand them and find a need for more generality.

as Greg Snow noted, you can use another form of regular expression that looks behind matches:

sub( '(?<=.{3})', 'd', old, perl=TRUE )

and could also build my dynamic gsub above using sprintf rather than paste0:

lhs <- sprintf('^([a-z]{%d})([a-z]+)$', n-1)

or for his sub regular expression:

lhs <- sprintf('(?<=.{%d})',n-1)

More Related Contents:

  1. Convert string to a variable name
  2. Making a string concatenation operator in R
  3. Removing html tags from a string in R
  4. How to split a string into substrings of a given length? [duplicate]
  5. How to convert variable (object) name into String [duplicate]
  6. Load R package from character string
  7. Getting and removing the first character of a string
  8. pass character strings to ggplot2 within a function
  9. Convert R vector to string vector of 1 element [duplicate]
  10. as.numeric with comma decimal separators?
  11. Count word occurrences in R
  12. converting datetime string to POSIXct date/time format in R
  13. Extract numeric part of strings of mixed numbers and characters in R
  14. Use character string as function argument
  15. How can I remove repeated characters in a string with R?
  16. How to collapse a list of characters into a single string in R
  17. Split a character vector into individual characters? (opposite of paste or stringr::str_c)
  18. Repeat and concatenate a string N times
  19. Extract the first (or last) n characters of a string
  20. Insert line breaks in long string — word wrap
  21. How to combine multiple character columns into a single column in an R data frame
  22. Ignore escape characters (backslashes) in R strings
  23. Convert integers to strings to create output filenames at run time
  24. What is the difference between \r\n, \r, and \n? [duplicate]
  25. Convert String to Float in Swift
  26. Number of Occurrences of a Character in NSString
  27. Swift, Strings and Memory Addresses
  28. Raw text strings for file paths in R
  29. Groovy String to Date
  30. Split a string every 5 characters

Leave a Comment