On May 22, 2008, at 8:56 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!
This should get you started:
with(list(x=sample(1:4, 10, prob=orig$Freq, replace=TRUE)), sapply
(1:4, function(k) sum(x==k)))
Or you can break it up in two steps (at the cost of creating a new
variable):
x <- sample(1:4, 10, prob=orig$Freq, replace=TRUE)
sapply(1:4, function(k) sum(x==k))
maja
Haris Skiadas
Department of Mathematics and Computer Science
Hanover College
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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