Re: [ferret_users] overlays + ppl = no overlays?

[Jaison Kurian <jaison@xxxxxxxxxxxxxxxxxx>]

Hi John,
          Sometimes the PPL command usage may be confusing. But, if you know
the rules, it is very easy to handle them. Relevant details are given below.
As an answer to your question, a simple example is also given toward the end.

  1. According to Ferret philosophy, the major PPL commands (like that for
       the plot title, axis labels/tics etc.) should be supplied with the
       very first plot (not with the overlays, it won't work!).

  2. In case you need to use a PPL command with an overlay plot, you need to
 
         plot/......./over/set_up
                            ! insert ppl commands here
         PPL plot/OVER

     The /OVER qualifier should be present both in plot command and in the
     ending "PPL plot" command. Sometimes, the script may work just fine 
     with a /OVER only to "PPL plot", but not safe with the vector commands.

  3. Some PPL Commands are stand alone (can be given anywhere in the script,
     before making the plot), some are not (which should be used between 
     "plot/set_up....." and "ppl plot") and some can be given only after making
     the plot. Please have a look at the following mail for details

     http://www.pmel.noaa.gov/maillists/tmap/ferret_users/fu_2006/msg00413.html


  4. The ppl commands are sensitive to the syntax (commas etc.). So refer to
     examples given in user manual, if a particular ppl command is not working
     for you.

Have a trial with the example given below. Please let me know if you have any
questions.....

Hope this helps....

Regards

Jaison


!------------Example begins here-------------------------------------------
\ cancel mode verify
!
! Description : A demo for the usage of ppl commands along with overlays. 
! 
! Doc         : On behaviour and usage of ppl commands 
!               http://www.pmel.noaa.gov/maillists/tmap/ferret_users/fu_2006/msg00413.html
!
! Created On  : 11/Sep/2007, JK
!
!-------------------------------------------------------------------------

  ! create two dummy variables

    define axis/x=1:150:1 xax

    let var1 = RANDU(x[gx=xax])
    let var2 = RANDN(x[gx=xax])

  ! ppl commands with the first plot

    plot/symbol=19/size=.2/color=blue/nolab/vlim=-2:2/set_up var1
       ppl title "Profiler Velocity (up=profiling=blue, down=return=red)"
    ppl plot
    plot/symbol=47/size=.2/color=red/nolab/over    var2

    pause 

  ! ppl commands with the second overlay plot 
   
    plot/symbol=19/size=.2/color=blue/nolab/vlim=-2:2    var1
    plot/symbol=47/size=.2/color=red/nolab/over/set_up   var2
       ! insert ppl commands here
    ppl plot/over

!------------Example ends here---------------------------------------------

On Mon, 10 Sep 2007, John Graybeal wrote:

> I am trying to plot multiple scatterplots on a single pair of axes, as in:
> 
> 1)  plot/symbol=19/size=.2/color=blue/vlimit=0:1:0.25/nolabel upV
> 2)  plot/symbol=47/size=.2/color=red/vlimit=0:1:0.25/overlay/nolabel downV
> 
> This works.  Now I'd like to add custom labels, as in
> 
> 3)  ppl title "Profiler Velocity (up=profiling=blue, down=return=red)"
> 4)  ppl plot
> 
> This also works, except...the first plotted variable (upV) has disappeared, only downV is plotted.
> 
> I am aware of the concept of set_up and have tried it in various incantations (line 1, lines 1+2), tried making line 4 an overlay plot, tried mixing up the line orders...  I haven't found a sequence in which the final plot contains both sets of data AND the labels.  
> 
> The main documentation I found said "You have to be careful about the order of the PPL commands."  So can someone help me be careful?
> 
> Earlier I set some window characteristics, if that matters (aspect, size, margins).
> 
> John
> 
> 

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