Matrices given to pt? [was: [R] for loops and counters]

I think what is happening is that it is preserving attributes of the input.
e.g.
x <- 1:3
attr(x, "A") <- 23
pt(x, 3)
[1] 0.8044989 0.9303370 0.9711656
attr(,"A")
[1] 23

Note that attribute A was preserved.  Since matrices are just
vectors with a dim attribute that would imply the result.  I agree
that it would be a good idea to document it if it is intended.
Hi, people.

I was a bit intrigued by the message quoted below.  Indeed, if pt() is
given a matrix, it returns a matrix.  Should this feature be documented?
?pt speaks about "a vector of quantiles", and says nothing about the
type of what it returns.

The same might presumably apply to other distribution-related functions.

----- Forwarded message from Martyn Plummer <plummer at iarc.fr> -----

From: Martyn Plummer <plummer at iarc.fr>
Date: Thu Apr 10 10:07:01 2003
Subject: [R] for loops and counters

Peter,

You didn't say what goes wrong, but you mind find this version more useful

tstat <- (matrix(means, k,k, byrow=TRUE) - matrix(means, k,k,byrow=FALSE))/rms
pvalue <- 2*(1-pt(abs(tstat), df=df))
pvalue[upper.tri(pvalue)]

S is designed to allow you to work with "whole objects", which means that
for loops can (and should) be avoided.

Martyn

On 05-Oct-99 Peter B. Mandeville wrote:
I am trying to assign values to a vector (pvalue). Similar code works in C
but not in R. What am I doing wrong?

      r <- pvalue <- 0
      for(i in (1:(k-1))){
              for(j in (i+1):k){
                      r <- r+1
                      tstat <- (means[i]-means[j])/rms
                      pvalue[r] <- 2*(1-pt(abs(tstat),df))
              }
      }
-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-
r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html
Send "info", "help", or "[un]subscribe"
(in the "body", not the subject !)  To: r-help-request at stat.math.ethz.ch
_._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._

----- End forwarded message -----

--
Fran?ois Pinard   http://pinard.progiciels-bpi.ca

______________________________________________
R-devel at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel

Matrices given to pt? [was: [R] for loops and counters]

Thread (3 messages)