# [R] check without loop

Scott, Uriel uriel.scott at mirant.com
Wed Mar 20 19:45:33 CET 2002

```I think the which() function would be helpful.  For example if x is a vector
and c some value then

> which( x == c )

will return a vector of those indices i of x for which x[i] = c.  Then you
can test whether that vector
has length 0.

> -----Original Message-----
> From:	jimi adams [SMTP:imij at columbus.rr.com]
> Sent:	Wednesday, March 20, 2002 11:41 AM
> To:	r-help at stat.math.ethz.ch
> Subject:	[R] check without loop
>
> i am probably just missing this one, but how can i check to see if a
> number
> is a part of a vector?
>
> i know i could do a loop checking for equivalence for each element, but i
> am
> thinking that there must be a simpler way to do it than that ( i think
> that
> i have even done it in the past, but can't remember how!)
> thanks
>
> what i am working with:
> (hope this makes sense)
>
> arclist
>   [1]   2   2   6   7   8   9   9  11  11  11  12  13  14  15  16  17  19
> 21
>  [19]  22  23  24  25  25  29  29  30  32  34  35  35  38  39  40  40  41
> 42
>  [37]  43  44  45  46  47  48  49  50  51  52  53  54  57  58  59  60  61
> 61
>  [55]  61  61  61  61  61  61  61  61  61  61  61  61  61  61  61  61  61
> 61
>  [73]  61  61  61  61  61  61  61  61  61  61  62  65  67  68  68  69  71
> 72
>  [91]  75  76  77  79  81  82  83  84  84  85  86  87  88  90  91  92  93
> 94
> [109]  95  96  96  96  96 100
>
> # and am sampling from a different list
> # if i draw, say 80, i would then not want to proceed, but if i draw a
> number on arclist i do
>
>
>
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```