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Groups > comp.lang.forth > #49284

Re: Selecting items in a vector

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WJ wrote:

> R:
> 
>   Create a vector of random integers:
> 
>   > sample(-3:5, 22, rep=TRUE) -> v
>   > v
>    [1]  5  2 -3  2  4 -1 -2 -3 -3 -1  4  4 -1  0  0 -2 -2  1  2  0  0  3
> 
>   Find the indices at which v < 0:
> 
>   > which(v < 0)
>   [1]  3  6  7  8  9 10 13 16 17
> 
>   Extract the negative numbers:
> 
>   > v[which(v < 0)]
>   [1] -3 -1 -2 -3 -3 -1 -1 -2 -2
> 
> How much easier is it in ANS Forth?

That was regrettable newbie prolixity.

  > v<0
   [1] FALSE FALSE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE FALSE FALSE
  [13]  TRUE FALSE FALSE  TRUE  TRUE FALSE FALSE FALSE FALSE FALSE
  > v[v<0]
  [1] -3 -1 -2 -3 -3 -1 -1 -2 -2

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Selecting items in a vector "WJ" <w_a_x_man@yahoo.com> - 2016-07-21 18:05 +0000
  Re: Selecting items in a vector "WJ" <w_a_x_man@yahoo.com> - 2016-07-21 18:11 +0000
    Re: Selecting items in a vector "WJ" <w_a_x_man@yahoo.com> - 2016-07-21 20:44 +0000

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