Re: log scale on Z axis

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

Hi, Ferret does not have a native capability to make 2-dimensional log 
plots. Here is a message from the archive, that we later made in to an FAQ:

http://ferret.pmel.noaa.gov/Ferret/Mail_Archives/fu_99/msg00230.html

http://www.ferret.noaa.gov/Ferret/FAQ/custom_plots/2D_log_plot.html

Here is a quick example of an X-Z plot, using the Levitus Climatology 
dataset that is released with Ferret. I don't do the fancy labeling but 
it would be similar to what is done in the above message. Note that the 
Z axis of the data has a depth of 0 at K=1, which has no log.  I use 0 
here, but you could use another value. One might define the axis using 0 
but not plot it (shade/k=2:20/y=0 temp...).  The axis you define must be 
monotonic.

yes? use levitus_climatology
yes? shade/y=0 temp  ! without the log axis

yes? list z[gz=temp],  log(z[gz=temp])

            DATA SET: /home/ja9/tmap/fer_dsets/data/levitus_climatology.cdf
            DEPTH (m): 0 to 5000
Column  1: Z is Z (axis ZAXLEVITR)
Column  2: EX#2 is LOG(Z[GZ=TEMP])
                 Z   EX#2
0       /  1:     0.   ....
10      /  2:    10.  1.000
20      /  3:    20.  1.301
30      /  4:    30.  1.477
50      /  5:    50.  1.699
75      /  6:    75.  1.875
100     /  7:   100.  2.000
150     /  8:   150.  2.176
200     /  9:   200.  2.301
300     / 10:   300.  2.477
400     / 11:   400.  2.602
600     / 12:   600.  2.778
800     / 13:   800.  2.903
1000    / 14:  1000.  3.000
1200    / 15:  1200.  3.079
1500    / 16:  1500.  3.176
2000    / 17:  2000.  3.301
3000    / 18:  3000.  3.477
4000    / 19:  4000.  3.602
5000    / 20:  5000.  3.699

yes? define axis/depth/z/units="log meters"  zlog = if k gt 1 then 
log(z[gz=temp]) else 0 
yes? shade/y=0 temp[gz=zlog@asn]

The labeling would be similar to what is done in the FAQ.

Ansley

hengkek@nus.edu.sg wrote:

> Greetings
>
> How do I get ferret to contour/shade/fill in log scale for Z axis?
>
> I.e. something like:
>
> use "bathymetry.nc"
> fill/level=(1,100000,'log') depth
>
> Thanks for any pointers.  I found similar questions in the archives 
> but no replies there. 
> (http://ferret.pmel.noaa.gov/Ferret/Mail_Archives/fu_98/msg00165.html)
>
> regards
> -chk
> Physical Oceanography
> Singapore