R help - Dec 2003 - Basic question on function

One is an integer and the other is not.  Try

for (i in 1:5) print( identical( i, as.integer(1) ) )

---
Date: Fri, 12 Dec 2003 14:47:07 -0800 
From: John Welsh <jwelsh at skcc.org>
To: 'R-help at lists.R-project.org' <R-help at stat.math.ethz.ch> 
Subject: [R] Basic question on function "identical" 

 
 

> for(i in c(1:5))
+ {
+ print(identical(i,1))
+ }

[1] FALSE
[1] FALSE
[1] FALSE
[1] FALSE
[1] FALSE

Why don't I get:

[1] TRUE
[1] FALSE
[1] FALSE
[1] FALSE
[1] FALSE


John Welsh
Associate Professor
Sidney Kimmel Cancer Center
10835 Altman Row
San Diego, CA 92121
(858) 450-5990 ex.282
jwelsh at skcc.org





 --- On Fri 12/12, John Welsh < jwelsh at skcc.org > wrote:
From: John Welsh [mailto: jwelsh at skcc.org]
To: R-help at stat.math.ethz.ch
Date: Fri, 12 Dec 2003 14:47:07 -0800
Subject: [R] Basic question on function "identical"

<br><br>> for(i in c(1:5))<br>+ {<br>+
print(identical(i,1))<br>+ }<br><br>[1] FALSE<br>[1]
FALSE<br>[1] FALSE<br>[1] FALSE<br>[1]
FALSE<br><br>Why don't I get:<br><br>[1]
TRUE<br>[1] FALSE<br>[1] FALSE<br>[1] FALSE<br>[1]
FALSE<br><br><br>John Welsh<br>Associate
Professor<br>Sidney Kimmel Cancer Center<br>10835 Altman
Row<br>San Diego, CA 92121<br>(858) 450-5990 ex.282<br>jwelsh
at
skcc.org<br><br>______________________________________________<br>R-help
at stat.math.ethz.ch mailing
list<br>https://www.stat.math.ethz.ch/mailman/listinfo/r-help<br>

In that particular case there is also 

which.max(x)

--- 
Date: Sat, 13 Dec 2003 13:31:42 -0000 (GMT) 
From: <Ted.Harding at nessie.mcc.ac.uk>
To: Martin Maechler <maechler at stat.math.ethz.ch> 
Cc: <R-help at stat.math.ethz.ch> 
Subject: Re: [R] Basic question on function "identical" 

 
 
On 13-Dec-03 Martin Maechler wrote:
> In general, use
> 
> == for testing equality of integer numbers (of type "integer"
> or not)
I hope this is not a suggestion to avoid usage like

which(x == max(x))

when x is a vector of reals? (i.e. should be OK when you know that
the thing on one side of == should be an exact copy in its internal
representation of the thing on the other side, if equality in the
usual sense holds).

In other words, I hope that (for instance) max(x) does not differ
internally from whichever of x[1] , ... , x[N] has the largest value ...
> all.equal for testing (near)equality non-integer numbers, and
> many other more structured objects.
> 
> identical only if you understand more about the S language ;-)
Cheers,
Ted.


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Date: 13-Dec-03 Time: 13:31:42
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