To remove double spaces and dates from strings, we can use the following regular expression:

gsub("\\b(?:End(?:\\s+DATE|(?:ing)?)|(?:0?[1-9]|1[012])(?:[-/.](?:0?[1-9]|[12][0-9]|3[01]))?[-/.](?:19|20)?\\d\\d)\\b|([\\s»]){2,}", "\\1", x, perl=TRUE, ignore.case=TRUE)

Here’s a breakdown of how it works:

• \\b matches the boundary between a word character and something that is not a word character.
• (?:End(?:\\s+DATE|(?:ing)?)|...) groups two alternatives:
  • The first one, End, captures only if followed by " DATE" or " ing".
  • The second one matches the date pattern \d{2} (two digits).
• (?:0?[1-9]|1[012])(?:[-/.](?:0?[1-9]|[12][0-9]|3[01]))?[-/.]?(19|20)? groups two alternatives:
  • The first one, 0?, matches an optional leading zero.
  • The second one, [1-9], matches any single digit from 1 to 9, or 1[012] if the previous character is between 01 and 12. This part can also be matched by simply [0-9]{2} without the parentheses.

Explanation

The regular expression works as follows:

• It first checks for “End” followed by optional dates (“DATE”) or “ing”. The ?i flag makes the match case-insensitive.
• If it matches, it removes the matched string from the input and returns the original string.

Last modified on 2024-10-23