Is this what you want?
> xtabs(Freq ~ Var1 + Var2, data = orig)
Var2
Var1 A B
A 40 30
B 5 25
See ?xtabs
Or is this what you want?
expand.dft <- function(x, na.strings = "NA", as.is = FALSE, dec = ".")
{
DF <- sapply(1:nrow(x), function(i) x[rep(i, each = x$Freq[i]), ],
simplify = FALSE)
DF <- subset(do.call("rbind", DF), select = -Freq)
for (i in 1:ncol(DF))
{
DF[[i]] <- type.convert(as.character(DF[[i]]),
na.strings = na.strings,
as.is = as.is, dec = dec)
}
DF
}
DF <- expand.dft(orig)
> str(DF)
'data.frame': 100 obs. of 2 variables:
$ Var1: Factor w/ 2 levels "A","B": 1 1 1 1 1 1 1 1 1 1 ...
$ Var2: Factor w/ 2 levels "A","B": 1 1 1 1 1 1 1 1 1 1 ...
HTH,
Marc Schwartz
on 05/22/2008 07:56 AM maiya wrote:
sorry, my mistake!
the data frame should read:
orig<-as.data.frame.table(orig)
orig
Var1 Var2 Freq
1 A A 40
2 B A 5
3 A B 30
4 B B 25
but basicaly i would simply like a sample of the original matrix ( which is
a frequency table/contingency table/crosstabulation)
hope this is clearer now!
maja
jholtman wrote:
Not exactly clear what you are asking for. Your data.frame.table does not
seem related to the original 'orig'. What exactly are you expecting as
output?
On Wed, May 21, 2008 at 10:16 PM, maiya <[EMAIL PROTECTED]> wrote:
i appologise for the trivialness of this post - but i've been searching
the
forum wothout luck - probably simply because it's late and my brain is
starting to go..
i have a frequency table as a matrix:
orig<-matrix(c(40,5,30,25), c(2,2))
orig
[,1] [,2]
[1,] 40 30
[2,] 5 25
i basically need a random sample say 10 from 100:
[,1] [,2]
[1,] 5 2
[2,] 0 3
i got as far as
orig<-as.data.frame.table(orig)
orig
Var1 Var2 Freq
1 A A 10
2 B A 5
3 A B 30
4 B B 25
and then perhaps
individ<-rep(1:4, times=orig$Freq)
which gives a vector of the 100 individuals in each of the 4 groups -
cells,
but I'm
(a) stuck here and
(b) afraid this is a very round-about way at getting to what I want i.e.
I
can now sample(individ, 10), but then I'll have a heck of a time getting
the
result back into the original matrix form....
sorry again, just please tell me the simple solution that I've missed?
thanks!
maja
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