ifelse()

I have a problem with ifelse(), I do not understand how it works.
X<-c(2,2,1,1,0,0)
str(X)
num [1:6] 2 2 1 1 0 0
Y<-ifelse(X>0,1,0)
Y
[1] 1 1 1 1 0 0

Can some one explain what is going on, I do not understand what ifelse is
doing in this case. Can someone explain the output Y.

Thanks
View this message in context: http://www.nabble.com/ifelse%28%29-tp21943309p21943309.html
Sent from the R help mailing list archive at Nabble.com.
It is checking the series of values of X and returning a series of 1  
and 0's;
    1 if it meets your condition (X>0) and
    0 if it doesn't.

What did you expect?

A more complex invocation might look like this:
 > ifelse( X > 0, 1:3, -1:-2)
[1]  1  2  3  1 -1 -2
Note the recycling of the elements of the yes and no arguments

Consider also:

 > (X>0)+0
[1] 1 1 1 1 0 0
David Winsemius
On Feb 10, 2009, at 4:44 PM, kayj wrote:

>
> I have a problem with ifelse(), I do not understand how it works.
>
>> X<-c(2,2,1,1,0,0)
>> str(X)
> num [1:6] 2 2 1 1 0 0
>> Y<-ifelse(X>0,1,0)
>> Y
> [1] 1 1 1 1 0 0
>>
>
> Can some one explain what is going on, I do not understand what  
> ifelse is
> doing in this case. Can someone explain the output Y.
>
> Thanks
>
> -- 
> View this message in context: http://www.nabble.com/ifelse%28%29-tp21943309p21943309.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
> R-help at r-project.org 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.
I have a problem with ifelse(), I do not understand how it works. 

X<-c(2,2,1,1,0,0)
str(X)
 num [1:6] 2 2 1 1 0 0
Y<-ifelse(X>0,1,0)
Y
[1] 1 1 1 1 0 0

Can some one explain what is going on, I do not understand what ifelse is
doing in this case. Can someone explain the output Y.
ifelse evaluates the condition given in its first argument and returns
the value of the second argument for all cases found to be TRUE and
the value of the third argument otherwise. As the first 4 elments of X
fulfill your condition (X>0) the corresponding result for them is 1 and
the rest 0.

See ?ifelse for details.

cu
	Philipp
Dr. Philipp Pagel
Lehrstuhl f?r Genomorientierte Bioinformatik
Technische Universit?t M?nchen
Wissenschaftszentrum Weihenstephan
85350 Freising, Germany
http://mips.gsf.de/staff/pagel