[R] matrix manipulations
Petr Klasterecky
klaster at karlin.mff.cuni.cz
Wed Feb 28 19:16:16 CET 2007
Don't know what's wrong - it works:
> data100
y X0 X1 X2 X3 ind
[1,] 11 1 2.79581511 -23.33335477 -33.6123061 1
[2,] 8 1 21.43289242 21.52826214 3.8415209 2
[3,] 6 1 6.18688631 21.51057247 -50.5547410 3
[4,] 12 1 -5.95172686 13.74167916 -16.1798745 4
<snip>
> data100[y]
[1] 9 10 8 18 10 10 9 7 11 11 7 10 9 14 7 18 9 7 10 10 18 10
9 11 9 10 11 11 11 10 8 9 8 7 18 9 11 15 7
[40] 10 7 9 7 18 11 11 18 11 11 18 7 10 11 7 11 10 18 7 9 9 9
7 7 7 14 18 18 14 11 12 11 8 15 7 7 9 18 14
[79] 10 7 7 12 7 7 9 8 7 8 11 7 15 18 18 7 15 7 7 11 11 10
These can pretty well be Poisson(10) variates... Remind that R is
case-sensitive in names, y and Y is not the same.
However, I really hope you are not using the code given below since it
is, well... very original... to generate something 100 times and to keep
just the last value at the end.
Petr
Anup Nandialath napsal(a):
> Dear friends,
>
> I have a basic question with R. I'm generating a set
> of random variables and then combining them using the
> cbind statement. The code for that is given below.
>
> for (i in 1:100)
> {
> y <- rpois(i,lambda=10)
> X0 <- seq(1,1,length=i)
> X1 <- rnorm(i,mean=5,sd=10)
> X2 <- rnorm(i,mean=17,sd=12)
> X3 <- rnorm(i,mean=3, sd=24)
> ind <- rep(1:5,20)
> }
>
> data100 <- cbind(y,X0,X1,X2,X3,ind)
>
> but when i look at the data100 table, the y values now
> take the observation count. (ie) the data under Y is
> not the poisson random generates but the observation
> number. Hence the last vector (ind) does not have a
> header. Is there any way i can drop the number of
> observation counts being added into the matrix.
>
> Thanks in advance for your help.
>
> Sincerely
>
> Anup
--
Petr Klasterecky
Dept. of Probability and Statistics
Charles University in Prague
Czech Republic
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