6.13 Sub Strings in Base R

20210330 The base function base::substr() can be used to extract and replace parts of a string similar to stringr::str_sub() in the tidyverse. Note however that it does not handle negative values and that string replacement only replaces the same length as the replacement string, without changing the length of the original string.

s <- "string manipulation"
substr(s, start=3, stop=6)
## [1] "ring"
substr(s, 3, 6)
## [1] "ring"
substr(s, 1, 12) <- "stip"
s
## [1] "stipng manipulation"

The base::substring() function performs similarly though uses last= rather than stop=.

s <- "string manipulation"
substring(s, first=3, last=6)
## [1] "ring"
x <- c("abcd", "aabcb", "babcc", "cabcd")
substring(x, 2, 4)
## [1] "bcd" "abc" "abc" "abc"
substring(x, 2, 4) <- "AB"
x
## [1] "aABd"  "aABcb" "bABcc" "cABcd"


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