# Re: reshape and get x axis data onto z axis

Hi Rob,
The /ORDER qualifier is available for NetCDF data sets, so that
might be of use.  Also, stay tuned for some "transpose" functions
which should be available in the next release which will transpose
axes for a variable.

Ansley

Rob Scott wrote:

Hi Ansley

Thanks very much for greatly clarifying the RESHAPE function.

Unfortunately the suggestion using ncdump and ncgen didn't work because the data is still in
the wrong order.

However, in that spirit, but using the LIST command to output to ASCII and the FILE command, together with
obvious choices of the /ORDER qualifier allowed me to force it onto the desired grid.

Thanks,
Rob

At 11:41 AM 12/3/2002 -0800, you wrote:

Hi Rob,
The RESHAPE function keeps the data in its internal order,
just wrapping it onto the newly specified grid.  The last step
you describe would require the function to shuffle the ordering
of the data which it doesn't do.   Try this example to see what
is happening.  I like to use STAT to see the size and shape
of the variables, but the LIST commands really show what's
going on.

yes? def axis/x=1:3:1 xax
yes? def axis/y y_irr = {1,3,4,5}
yes? def axis/z=1:5:1 zax
yes? let a = i[gx=xax] + 10*j[gy=y_irr] + 100*k[gz=zax]
yes? stat a
yes? list a
VARIABLE : I[GX=XAX] + 10*J[GY=Y_IRR] + 100*K[GZ=ZAX]
SUBSET   : 3 by 4 by 5 points (X-Y-Z)
1      2      3
1      2      3
---- K:1 Z:   1
1   / 1:  111.0  112.0  113.0
3   / 2:  121.0  122.0  123.0
4   / 3:  131.0  132.0  133.0
5   / 4:  141.0  142.0  143.0
---- K:2 Z:   2
1   / 1:  211.0  212.0  213.0
3   / 2:  221.0  222.0  223.0   ...

yes? def axis/t=2:10:2 tnew
yes? sh axis tnew
yes? def grid/x=xax/y=y_irr/t=tnew zytgrid
yes? let dum = 0*x[g=zytgrid]+0*y[g=zytgrid]+0*t[g=zytgrid]
yes? stat dum

yes? let b = reshape(a,dum)
yes? stat b
yes? list b
VARIABLE : RESHAPE(A,DUM)
SUBSET   : 3 by 4 by 5 points (X-Y-T)
1      2      3
1      2      3
---- L:1 T:   2
1   / 1:  111.0  112.0  113.0
3   / 2:  121.0  122.0  123.0
4   / 3:  131.0  132.0  133.0
5   / 4:  141.0  142.0  143.0
---- L:2 T:   4
1   / 1:  211.0  212.0  213.0
3   / 2:  221.0  222.0  223.0

yes? def axis/z=3:9:3 znew
yes? def grid/y=y_irr/z=znew/t=tnew yztgrid
yes? let dum =  0*y[g=yztgrid]+0*z[g=yztgrid]+0*t[g=yztgrid]
yes? stat dum

yes? let c = reshape(b,dum)
yes? stat c
yes? list c
VARIABLE : RESHAPE(B,DUM)
SUBSET   : 4 by 3 by 5 points (Y-Z-T)
1      3      4      5
1      2      3      4
---- L:1 T:   2
3   / 1:  111.0  112.0  113.0  121.0
6   / 2:  122.0  123.0  131.0  132.0
9   / 3:  133.0  141.0  142.0  143.0
---- L:2 T:   4
3   / 1:  211.0  212.0  213.0  221.0
6   / 2:  222.0  223.0  231.0  232.0

You can see how the data is staying in its original order; the
K axis does not automatically contain the data from the I axis.
What you could do, is write a NetCDF file with the data at the
point where you have it in X, Y, and T.  Use NCDUMP to write
this out in ASCII format, edit the file and rename the X axis
to a Z axis, also making sure the order of the axes listed in the
NetCDF file is correct in all the header sections of the file.  Then
use NCGEN to create a file in the ordering you want.

Ansley Manke

Rob Scott wrote:

Dear ferret

I have a netCDF file with a three dimensional field on the x, y, z axes.
I would like to use zaxreplace on the x axis data. (I believe this amazing function is currently only supported on the z-axis.)

I've managed to use RESHAPE to get the z axis data onto the t-axis, but when I try to use RESHAPE to get the x-axis data onto the
now vacant z-axis, it messes up the data. Am I trying to do the impossible?

The manual states:

"For any axis X,Y,Z, or T if the axis is the same in the input and output grids then the region from argument 1 will be preserved in the output.
This implies that when the above technique is used on multi-dimensional input, only the axes which differ between the input and output grids are affected by the RESHAPE operation."

Hence I've attempted to "let ferret know" that I want to move the x-data over to the z-axis, and leave y and t alone, by defining my output grid to have only one dimension in the x-direction,
In particular:

DEFINE AXIS/x=1:1:1 xaxis_normal                                                                                       ! my attempt to make this a normal axis
DEFINE AXIS/z=1:5:1 zaxis_new                                                                                            ! (the old x - axis)
DEFINE GRID/LIKE=old_grid/ x= xaxis_normal/ z=zaxis_new   output_grid                 ! I need to use LIKE to get the y-axis correct because it's irregular.

LET dummie = x[output_grid] * y[output_grid]  * z[output_grid]  *t[output_grid]

LET new_var = RESHAPE(old_var,dummie]

But now
old_var[i=1]      .NE.       new_var[k=1]

Rob

Rob Scott
Research Associate
Institute for Geophysics
University of Texas at Austin
4412 Spicewood Springs Rd.
Building 600
Austin, TX
78759

Office: +1-512-471-0375

--
Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA  (206)526-6246

Rob Scott
Research Associate
Institute for Geophysics
University of Texas at Austin
4412 Spicewood Springs Rd.
Building 600
Austin, TX
78759

Office: +1-512-471-0375

--
Ansley Manke  Pacific Marine Environmental Laboratory  Seattle WA  (206)526-6246