From wwl107 at psu.edu  Wed Jun 22 04:46:49 2005
From: wwl107 at psu.edu (wwl107@psu.edu)
Date: Wed, 22 Jun 2005 04:46:49 +0200 (CEST)
Subject: [Rd] Trouble with ifelse and if statement (PR#7962)
Message-ID: <20050622024649.D4BEEA22C@slim.kubism.ku.dk>

Full_Name: Woolton Lee
Version: 2.1
OS: windows
Submission from: (NULL) (128.118.224.46)


I did the following ('g' and 'h' are both numeric vectors)
> i <- abs(g-h)
creating a vector 'i' with values,
> i
 [1] 0.08 0.00 0.33 0.00 0.00 0.00 0.00 0.33 0.00 0.00 0.08 0.08 0.20 0.00 0.13

Now, I want to create a new vector =1 whenever 'i' = 0.33 and =0 otherwise.  I
use the 'ifelse' function to do this but when I do, I find
> ifelse(i==0.33,1,0)
 [1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

even though the third and eighth elements of 'i' clearly equal 0.33.  Unless I
have missed something, 'ifelse' should return a vector that looks like,
[1] 0 0 1 0 0 0 0 1 0 0 0 0 0 0 0

When I try 0.13 I get a correct result
> ifelse(i==0.13,1,0)
 [1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1

but when I try 0.08 or 0.2 I find a similar problem,
> ifelse(i==0.08,1,0)
 [1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> ifelse(i==0.20,1,0)
 [1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> ifelse(i==0.2,1,0)
 [1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Can you explain what is happening?  Why is R incorretly returning a vector that
does not reflect the values in 'i'?  Is this due to a malfunction in R or have I
missed something?

Thank you for your help.

Woolton



[Rd] Trouble with ifelse and if statement (PR#7962)
wwl107@psu.edu