On 12/12/06, Leeds, Mark (IED) <[EMAIL PROTECTED]> wrote: > ifelse is vectorized but there is no way you could know what's > happening with that command > because you have rnorm(1) for both conditions. I think you mean to have > something different in one of them ? > > Whewn I run your code in my R session, I get 10 values for y1, so there > isn't anything wrong except > That you have the same statement for both cases.
But you got only two (eventually one) distinct values, right? Look at the code for 'ifelse': yes and no are only called once each, then recycled to desired length. I guess you want something like x <- rnorm(10) y <- rnorm(10) z <- rnorm(10) y1 <- ifelse(x > 0, y, z) but this whole business is probabilistically the same as x <- rnorm(10) y1 <- rnorm(10) which of course is faster and more transparent. Göran > > > > > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of > [EMAIL PROTECTED] > Sent: Tuesday, December 12, 2006 3:13 PM > To: [email protected] > Subject: [R] ifelse question > > Dear R-helpers, > How come that in the following code the rnorm() function is evaluated > only once for each branch of the 'ifelse' ? > > x <- rnorm(10) > y1 <- ifelse(x > 0, rnorm(1) , rnorm(1)) > > > What is the right way to make it called/evaluated for each row, apart > from a 'for' loop ? > > Thanks, > > Jacques. > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -------------------------------------------------------- > > This is not an offer (or solicitation of an offer) to buy/se...{{dropped}} > > ______________________________________________ > [email protected] mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > -- Göran Broström ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
