Re: [ferret_users] [ferret] compress, expand variable

[Ansley Manke <ansley.b.manke@xxxxxxxx>]

Hi Patrick,
there are also the family of functions compress*_by will do this, but 
expressing the mask is a bit different:

yes? show function compressi_by
COMPRESSI_BY(dat,mask)
   Compress arg1 by (multi-D) mask in arg 2
   dat: variable to compress on I axis
   mask: valid/bad points guiding compression (multi-D)

yes? let a = {101,202,303,404,505,606,707,808,909}
yes? let b = {,,1,,,1,1,,1}
yes? list compressi_by(a,b)
            VARIABLE : COMPRESSI_BY(A,B)
            SUBSET   : 9 points (X)
1   / 1:  303.0
2   / 2:  606.0
3   / 3:  707.0
4   / 4:  909.0
5   / 5:   ....
6   / 6:   ....
7   / 7:   ....
8   / 8:   ....
9   / 9:   ....



Patrick Brockmann wrote:

> Hi all,
>
> Is there a way to compress a variable from
> a selection of index ?
>
> Here is an example of what I am looking for:
> let A={101,202,303,404,505,606,707,808,909}
> let B={3,6,7,9}
>
> Now, I would like to get a new variable C to work on A from the 
> selected indexes B.
> This new variable C will be equal to :
> 303,606,707,909
>
> Thanks for any idea on this topic
> Patrick