[R] If loops
John Fox
jfox at mcmaster.ca
Sun Oct 3 16:50:09 CEST 2004
Dear Laura,
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Laura Collins
> Sent: Sunday, October 03, 2004 8:32 AM
> To: R-help at stat.math.ethz.ch
> Subject: [R] If loops
>
> Hi,
>
>
>
> I'm a complete beginner to all this so I was hoping someone
> could help me!
>
>
>
> What I'm trying to do is to write a function that returns the
> coordinates where a vector x is equal to a. So say I invent
> a vector x:
>
>
> x<-c(,5,8,9,8,3).
>
> If a is a<-8.
>
>
>
> I want the function to return the coordinates of x where the
> number 8 appears (i.e. 2 4).
>
> I know I need to set up an if loop but I'm really not sure
> how to do this.
>
>
>
> Any advice or clues will be much appreciated.
>
> which(x == 8)
[1] 2 4
See ?which.
Note that your definition of x is in error (try it) and that <- in R means
assignment, not equality.
John
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