R: Examples for 'stringr::str

### ** Examples

hw <- "Hadley Wickham"

str_sub(hw, 1, 6)

[1] "Hadley"

str_sub(hw, end = 6)

[1] "Hadley"

str_sub(hw, 8, 14)

[1] "Wickham"

str_sub(hw, 8)

[1] "Wickham"

# Negative indices index from end of string
str_sub(hw, -1)

[1] "m"

str_sub(hw, -7)

[1] "Wickham"

str_sub(hw, end = -7)

[1] "Hadley W"

# str_sub() is vectorised by both string and position
str_sub(hw, c(1, 8), c(6, 14))

[1] "Hadley"  "Wickham"

# if you want to extract multiple positions from multiple strings,
# use str_sub_all()
x <- c("abcde", "ghifgh")
str_sub(x, c(1, 2), c(2, 4))

[1] "ab"  "hif"

str_sub_all(x, start = c(1, 2), end = c(2, 4))

[[1]]
[1] "ab"  "bcd"

[[2]]
[1] "gh"  "hif"

# Alternatively, you can pass in a two column matrix, as in the
# output from str_locate_all
pos <- str_locate_all(hw, "[aeio]")[[1]]
pos

     start end
[1,]     2   2
[2,]     5   5
[3,]     9   9
[4,]    13  13

str_sub(hw, pos)

[1] "a" "e" "i" "a"

# You can also use `str_sub()` to modify strings:
x <- "BBCDEF"
str_sub(x, 1, 1) <- "A"; x

[1] "ABCDEF"

str_sub(x, -1, -1) <- "K"; x

[1] "ABCDEK"

str_sub(x, -2, -2) <- "GHIJ"; x

[1] "ABCDGHIJK"

str_sub(x, 2, -2) <- ""; x

[1] "AK"

Examples for 'stringr::str_sub'