Dear R- User
I created two random number sets using rnorm function and calcuted their
respective means. However now I would like to randomly
replace some values with NA. Thus create my own test data.
Any help or suggestions on this ?
Also wanted to confirm when multiplying two random number vectors x am y by
matrix..is this how i do it.
A is the matrix
z <- c(x,y) # x and y the two set of vectors
w <- A%*%Z # each element in each vector multipled by the matrix .
regards
Kunal
Let's say x is of size 100.
x <- rnorm(100)
x[sample(1:100,10)] <- NA
Kunal Shetty <kshe4 at student.monash.edu>
Sent by: r-help-bounces at stat.math.ethz.ch
10/27/2004 12:59 PM
To: r-help at stat.math.ethz.ch
cc:
Subject: [R] Random number
Dear R- User
I created two random number sets using rnorm function and calcuted their
respective means. However now I would like to randomly
replace some values with NA. Thus create my own test data.
Any help or suggestions on this ?
Also wanted to confirm when multiplying two random number vectors x am y
by matrix..is this how i do it.
A is the matrix
z <- c(x,y) # x and y the two set of vectors
w <- A%*%Z # each element in each vector multipled by the matrix .
regards
Kunal
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Kunal Shetty wrote:> Dear R- User > > I created two random number sets using rnorm function and calcuted their respective means. However now I would like to randomly > replace some values with NA. Thus create my own test data. > Any help or suggestions on this ? > >Use ?sample: n <- 100 x <- rnorm(n) x[sample(n, 4)] <- NA sum(is.na(x)) # [1] 4> Also wanted to confirm when multiplying two random number vectors x am y by matrix..is this how i do it. > A is the matrix > > z <- c(x,y) # x and y the two set of vectors > > w <- A%*%Z # each element in each vector multipled by the matrix . >(Be careful: R is case sensitive (z != Z).) I'm not really clear what you want here. "%*%" is matrix multiplication and "*" is elementwise multiplication. Also using "c" makes a vector or length "n = length(x) + length(y)". This implies that "A" above "p x n" (i.e. p rows, n columns) and the result "w" would be "p x 1". Please provide an example of what you expect to see by the multiplication. --sundar> > regards > Kunal > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html