DATA
I have data from two (or more) locations with ID: 'A' and 'B'
for three (or more) YEARS: 1999 to 2001
of two (or more) variables: VAR1, VAR2.
> x
ID YEAR VAR1 VAR2
1 A 1999 9 2
2 B 1999 8 9
3 A 2000 2 3
4 B 2000 3 4
5 A 2001 9 5
6 B 2001 7 2
DESIRED RESULT
I want to calculate the rank of the values of each variable
for each location (ID) in every year.
I want to get the ranks in a dataframe 'x.ranked'
having the same structure as the original dataframe 'x'
(which should be ready for the use by lattice functions).
> x.ranked
ID YEAR VAR1 VAR2
1 A 1999 2 1
2 B 1999 1 2
3 A 2000 1 1
4 B 2000 2 2
5 A 2001 2 2
6 B 2001 1 1
EXAMPLE CODE
x <- data.frame(
ID = rep( c('A', 'B' ), 3 )
, YEAR = rep( c( 1999, 2000, 2001 ), each=2 )
, VAR1 = c( 9, 8, 2, 3, 9, 7 )
, VAR2 = c( 2, 9, 3, 4, 5, 2 )
)
vars <- c( 'VAR1', 'VAR2' )
fun <- function( x, group=NULL ){
if( ! is.null(group) ) by( x, group, fun )
else if( ! is.vector(x) ) sapply( x, fun )
else rank( x )
}
x.ranked <- fun( x[,vars], x$YEAR )
OBTAINED RESULT
I got the right values by using the function 'fun',
but the result does not have the desired structure.
Can anyone help me to get the desired structure?
> x.ranked
group: 1999
VAR1 VAR2
[1,] 2 1
[2,] 1 2
--------------
group: 2000
VAR1 VAR2
[1,] 1 1
[2,] 2 2
--------------
group: 2001
VAR1 VAR2
[1,] 2 2
[2,] 1 1
Wolfram
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