Re: [ferret_users] extracting info from axes

["William.S.Kessler" <William.S.Kessler@xxxxxxxx>]

Hi Ge Peng -

Any quantity that is written on a default plot is available as a symbol.

For example, if you:

plot/i=242/j=14/k=22/l=8 varname

The plot and title will contain the information you want (perhaps in  
the upper left corner, or in the title below the plot).

AFTER making such a plot, these symbols will be found by:

yes? ppl listsym

These symbols will generally be numbered lab4, lab5, lab6, ....  
(lab1,2,3 are the standard Ferret info that appears in the upper  
right corner of the plot).

You can write these in subsequent plots as follows:

label xpos ypos center angle size ($lab4)

And, you can get fancier by noticing that these label numbers are  
flagged by other symbols in the list. You don't have to do that long  
listing every time. For example, the label for the plot longitude (if  
it is relevant) is flagged by the symbol labnum_x. So, you can always  
write the longitude by:

label xpos ypos center angle size ($lab($labnum_x))

In addition to the location identifiers, there are also the labels  
for the dataset (flagged by labnum_dset) and others as appropriate.

The one rule to remember is that these symbols are defined ONLY AS  
THE PLOT IS DRAWN. You MUST make a standard plot (without /NOLABEL)  
to define them before you can use them.

Billy K


On 18/02/2009, at 4:19 PM, Ge Peng wrote:

> Hi Ferret Users,
>
> Apology if this request is too elementary.
>
> I would like to extract grid info from a data set for the purpose of
> labeling. For example, for a given region/i=242/j=14/k=22/l=8, I  
> have the
> lon, lat, z, and time as follows:
>
> yes? list x[gx=xt_ocean]
>              VARIABLE : X
>                         axis XT_OCEAN
>              LONGITUDE: 38.5W(-38.5)
>          -38.50
> yes? list y[gy=yt_ocean]
>              VARIABLE : Y
>                         axis YT_OCEAN
>              LATITUDE : 68.5S
>          -68.50
> yes?  list z[gz=zt_ocean]
>              VARIABLE : Z
>                         axis ZT_OCEAN
>              DEPTH (m): 215
>           215.0
>
> yes? list t[gt=TIME]
>              VARIABLE : T
>                         axis TIME
>              TIME     : 07-FEB-1999 12:00 JULIAN
>           2228.
>
> I would like to define a label, which should be something like
> "38.5W, 68.5S, DEPTH (m): 215, 07-FEB-1999"
>
> Of cause, it will be different for a different region if I change  
> i,j,k,
> or l values.
>
> Is it a way to create the label dynamically?
>
> Thanks,
>
> --- Peng