如何删除也有单词的R列中的固定数字？

Question

I have a vector that has a series of numbers and words.

df <- as.character(c(1234, "Other", 5678, "Abstain"))

I would like to remove the last two digits of the numbers without affecting the words in the string.

df <- as.character(c(12, "Other", 56, "Abstain"))

Answer 1

Probably a bit more robust/versatile/safe than the solution suggested by @r2evans in the comments.

gsub( "(\\d{2,})\\d{2}$", "\\1", df)

what it does:

pattern = "(^\\\\d{2,})\\\\d{2}$"

• ^ matches the start of the string
• \\\\d{2,} matches any substring of at least two digits (delete the comma of you only want to match strings of the exact length of 4 digits)
• (^\\\\d{2,}) the round brackets define the start from the string and the following repetition of minimal two digits as a group.
• \\\\d{2} a repetition of exactly two digits
• $ matches the end of a string

in short: it matches any string that exits solely of digits, that starts with a minimum of two digits, andd ends with two digits (so the minimum length of the digit string = 4)

replacement = "\\\\1"

• replaces the entire matches string woth the first defind group ( (^\\\\d{2,}) ) from the above described pattern.

sample data

df <- c(123, "Other", 5678, "Abstain", "b12345", 123456, "123aa345")

gsub("(^\\d{2,})\\d{2}$", "\\1", df)
#[1] "123"      "Other"    "56"       "Abstain"  "b12345"   "1234"     "123aa345"