Re: Selecting items in a vector

From	"WJ" <w_a_x_man@yahoo.com>
Newsgroups	comp.lang.forth
Subject	Re: Selecting items in a vector
Date	2016-07-21 20:44 +0000
Organization	A noiseless patient Spider
Message-ID	<nmrc7v$ahp$1@dont-email.me> (permalink)
References	<nmr2t3$5s2$1@dont-email.me> <nmr39b$79e$1@dont-email.me>

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WJ wrote:

> 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

Change all values < 0 to 90:

 > v[v<0] = 90
 > v
  [1]  5  2 90  2  4 90 90 90 90 90  4  4 90  0  0 90 90  1  2  0  0  3

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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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