Re: 3D to 2D

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

Hi,
I don't think your question reached the Users' List,
but here's a simple answer.  The function RESHAPE(A,B) 
wraps argument A onto the grid of argument B. We can 
define the output grid with an abstract X axis of length 
NX*NY, and the same time axis as the input grid, create 
a dummy variable on the output grid, then use RESHAPE
to define the output 2D variable

Here is a simple example:


! Define a small 3-D variable

yes? def axis/x=1:5:1 xax
yes? def axis/y=1:3:1 yax
yes? def axis/t=1:4:1 tax
yes? let var3d = x[gx=xax] + 10*y[gy=yax] + 100*t[gt=tax]
yes? list/l=1/j=1 var3d
            VARIABLE : X[GX=XAX] + 10*Y[GY=YAX] + 100*T[GT=TAX]
            SUBSET   : 5 points (X)
            Y        : 1
            T        : 1
            1    
            1
1   / 1:  111.0
2   / 2:  112.0
3   / 3:  113.0
4   / 4:  114.0
5   / 5:  115.0
yes? list/l=4/j=2 var3d
            VARIABLE : X[GX=XAX] + 10*Y[GY=YAX] + 100*T[GT=TAX]
            SUBSET   : 5 points (X)
            Y        : 2
            T        : 4
            2    
            2
1   / 1:  421.0
2   / 2:  422.0
3   / 3:  423.0
4   / 4:  424.0
5   / 5:  425.0

! Define a 2-D grid and a variable on it.

yes? def axis/x=1:`5*3`:1 space_ax
!-> def axis/x=1:15:1 space_ax
yes? let var2d = 0*x[gx=space_ax] + 0*t[gt=tax]

! Use the RESHAPE function to create the output 2-D variable.
! Check the values.

yes? let outvar = reshape(var3d,var2d)
yes? list/l=1 outvar
            VARIABLE : RESHAPE(VAR3D,VAR2D)
            SUBSET   : 15 points (X)
            T        : 1
1    /  1:  111.0
2    /  2:  112.0
3    /  3:  113.0
4    /  4:  114.0
5    /  5:  115.0
6    /  6:  121.0
7    /  7:  122.0
8    /  8:  123.0
9    /  9:  124.0
10   / 10:  125.0
11   / 11:  131.0
12   / 12:  132.0
13   / 13:  133.0
14   / 14:  134.0
15   / 15:  135.0
yes? list/l=4 outvar
            VARIABLE : RESHAPE(VAR3D,VAR2D)
            SUBSET   : 15 points (X)
            T        : 4
1    /  1:  411.0
2    /  2:  412.0
3    /  3:  413.0
4    /  4:  414.0
5    /  5:  415.0
6    /  6:  421.0
7    /  7:  422.0
8    /  8:  423.0
9    /  9:  424.0
10   / 10:  425.0
11   / 11:  431.0
12   / 12:  432.0
13   / 13:  433.0
14   / 14:  434.0
15   / 15:  435.0




R Prabowo wrote:

> Hi there,
>
> I have a 3D data (long, lat, time) size of (65, 33, 73). I want make this 3D data become a 2D data (long-lat, time or 65x33, 73). I have been trying to do it by using nested repeat command as script bellows. But up 1995 iteration, there is error saying that:
>
> **ERROR: a program limit has been reached: too many user-defined variables
>          cancel or redefine some variables
> DEFINE VARIABLE 5dcr2D1995=5dcr[i=45,j=31]
> Command file, command group, or REPEAT execution aborted
>
> The script I used is:
>
> can data/all
> can var/all
> SET MEMORY/SIZE=15
> use/regulart data.nc
> show data/full
> DEFINE AXIS/T=3-JAN:29-DEC/npoints=73 tpentad 
> LET zero=T[gt=tpentad@mod] * 0                      
> REPEAT/l=1:73 ( \
> REPEAT/j=1:33 ( \
> REPEAT/i=1:65 ( \
> let ij = `i`+(`j`-1)*65; \
> let 5dcr2D`ij`=5dcr[i=`i`,j=`j`]); \
> let 5dcr2D= 5dcr2D`ij`+zero[l=`l`]; \
> save/append/file= data2D.nc 5dcr2D))
>
> Is there any one has any elegant way to do this work? Thank you very much.
>
>
>