weight cases?

Try this (and round the result to make to it comparable to your calculation):

xtabs(weight ~ var1 + var2, my.data)

On 10/14/06, Adrian Dusa <dusa.adrian at gmail.com> wrote:

Thanks for this Gabor,

Sometimes weights can take various values, like 0.9

rep(letters[1:3], c(1, 0.9, 1.6))

[1] "a" "c"

What if the weight variable would be:

my.data$weight <- c(0.4, 2, 1.3, 0.9, 1)

The way I found the solution was to compute the unweighted table, then find
the weight for each unique combination and multiply that with the
corresponding row-column entry in the table. The solution though is not very
satisfactory:

my.data$var1 <- as.factor(my.data$var1)
my.data$var2 <- as.factor(my.data$var2)
total <- expand.grid(levels(my.data$var1), levels(my.data$var2))
rowsmy.data <- apply(unique(my.data[,1:2]), 1, paste, collapse="")
rowstotal <- apply(total, 1, paste, collapse="")
total$weight <- 0
total$weight[sapply(rowsmy.data, function(x) which(rowstotal == x))] <-
unique(my.data)[,3]

(unweighted <- table(my.data$var1, my.data$var2))
round(unweighted*total$weight, 0)


Yet another question: how would the weight variable be applied to correlate
two numerical variables?

Best,
Adrian

On Saturday 14 October 2006 16:00, Gabor Grothendieck wrote:

Try this:

    table(lapply(my.data, rep, my.data$weight)[1:2])

On 10/14/06, Adrian Dusa <dusa.adrian at gmail.com> wrote:

Dear all,

This is probably a stupid question for which I have a solution, which
unfortunately is not as straighforward as I'd like. I wonder if there's a
simple way to apply a weighting variable for the cases of a dataframe
(well I'm sure there is, I just cannot find it).

My toy example:

my.data <- data.frame(var1=c("c", "e", "a", "d", "b"),

                       var2=c("E", "B", "A", "C", "D"),
                       weight=c(1, 2, 1, 1, 1))

table(my.data$var1, my.data$var2)

   A B C D E
 a 1 0 0 0 0
 b 0 0 0 1 0
 c 0 0 0 0 1
 d 0 0 1 0 0
 e 0 1 0 0 0

Applying the weight variable, the table should yield a value of 2 for the
"eB"

combination:

table(my.data$var1, my.data$var2)

   A B C D E
 a 1 0 0 0 0
 b 0 0 0 1 0
 c 0 0 0 0 1
 d 0 0 1 0 0
 e 0 2 0 0 0


Thanks in advance,
Adrian

--
Adrian Dusa
Romanian Social Data Archive
1, Schitu Magureanu Bd
050025 Bucharest sector 5
Romania
Tel./Fax: +40 21 3126618 \
         +40 21 3120210 / int.101

--
Adrian Dusa
Romanian Social Data Archive
1, Schitu Magureanu Bd
050025 Bucharest sector 5
Romania
Tel./Fax: +40 21 3126618 \
         +40 21 3120210 / int.101