I have the following data frame:
sort_data <- data.frame(id=1:10,
var=c("A", "B", "C", "D", "E", "F", "G", "H", "I", "J"))
I would like to sort this data in a specific order (using the "id" column) :
sort_order <- c(4, 7, 2, 5, 9, 1, 3, 6, 8, 10)
Is there a quick way to do this in R?
You could sort by indices as was noted in comments,
sort_data[sort_order, ]
# id var
# 4 4 D
# 7 7 G
# 2 2 B
# 5 5 E
# 9 9 I
# 1 1 A
# 3 3 C
# 6 6 F
# 8 8 H
# 10 10 J
however, if the IDs don't match the range of indices like so
sort_data1 <- transform(sort_data, id=id + 10)
sort_order1 <- sort_order + 10
your code will break:
sort_data1[sort_order1, ]
# id var
# NA NA <NA>
# NA.1 NA <NA>
# NA.2 NA <NA>
# NA.3 NA <NA>
# NA.4 NA <NA>
# NA.5 NA <NA>
# NA.6 NA <NA>
# NA.7 NA <NA>
# NA.8 NA <NA>
# NA.9 NA <NA>
So it's safer to use match,
sort_data[match(sort_order1, sort_data1$id), ]
# id var
# 4 14 D
# 7 17 G
# 2 12 B
# 5 15 E
# 9 19 I
# 1 11 A
# 3 13 C
# 6 16 F
# 8 18 H
# 10 20 J
which also works in the first case.
sort_data[match(sort_order, sort_data$id), ]
# id var
# 4 4 D
# 7 7 G
# 2 2 B
# 5 5 E
# 9 9 I
# 1 1 A
# 3 3 C
# 6 6 F
# 8 8 H
# 10 10 J
If you have missings (i.e. NAs) in your IDs, you may wrap a na.omit(match(.)) around, note however that those IDs will be deleted.