Generate a sequence of characters from 'A'-'Z'

问题

I can make a sequence of numbers like this:

s = seq(from=1, to=10, by=1)

How do I make a sequence of characters from A-Z? This doesn't work:

seq(from=1, to=10)

回答1:

Use LETTERS and letters (for uppercase and lowercase respectively).

回答2:

Use the code you have with letters and/or LETTERS:

> LETTERS[seq( from = 1, to = 10 )]
 [1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J"
> letters[seq( from = 1, to = 10 )]
 [1] "a" "b" "c" "d" "e" "f" "g" "h" "i" "j"

回答3:

Just use the predefined variables letters and LETTERS.

And for completeness, here it something using seq:

R> rawToChar(as.raw(seq(as.numeric(charToRaw('a')), as.numeric(charToRaw('z')))))
[1] "abcdefghijklmnopqrstuvwxyz"
R> 

回答4:

R.oo package has an intToChar function, that uses ASCII values, if LETTERS and letters aren't any good. A is 65 in ASCII:

> require(R.oo)
> intToChar(65:79)
 [1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O"

or you can use the fact that the lowest unicode numbers are ascii and hence intToUtf8 in R-base like this:

> intToUtf8(65:78,multiple=TRUE)
 [1] "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N"

or faff around with rawToChar:

> rawToChar(as.raw(65:78))
[1] "ABCDEFGHIJKLMN"

来源：https://stackoverflow.com/questions/4370033/generate-a-sequence-of-characters-from-a-z