On 03/14/2011 10:32 AM, array chip wrote:
Hi, I have a character vector as below:
a<-c('10','3R','4','4R','5','5R','6','6R','7','8','9','7R','1','10R','11'
,'11R','12','12R','13','13R','14','14R','15','15R','1R','2','2R','3','8R'
,'9R')
Is there a clever way to sort this easily to return a vector of index that would
produce a vector as below:
a[index]:
[1] "1" "2" "3" "4" "5" "6" "7" "8" "9" "10"
[11] "11" "12" "13" "14" "15" "1R" "2R" "3R" "4R" "5R"
[21] "6R" "7R" "8R" "9R" "10R" "11R" "12R" "13R" "14R" "15R"
treat these as levels of a factor and let R do the thinking
lvls = c(1:15, paste(1:15, "R", sep=""))
a = factor(c('10', '3R', '4', '4R', '5', '5R', '6', '6R', '7', '8',
'9', '7R', '1', '10R', '11', '11R', '12', '12R', '13',
'13R', '14', '14R', '15', '15R', '1R', '2', '2R', '3',
'8R' , '9R'), levels=lvls)
> sort(a)
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14
[15] 15 1R 2R 3R 4R 5R 6R 7R 8R 9R 10R 11R 12R 13R
[29] 14R 15R
30 Levels: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1R 2R ... 15R
> a[order(a)]
[1] 1 2 3 4 5 6 7 8 9 10 11 12 13 14
[15] 15 1R 2R 3R 4R 5R 6R 7R 8R 9R 10R 11R 12R 13R
[29] 14R 15R
30 Levels: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1R 2R ... 15R
Martin
Thanks,
John
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