Re: [ferret_users] Plotting a simple box outline?

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

Hi Luke,
Glad to hear you've got your script going.

Is your plot showing the region you intended? The SET REGION command that you used in the script in the original question is NOT applied when you call fland. Unless you are overlaying land masses on another plot, you would do better with a call to the basemap.jnl script.  But perhaps that was just a portion of your script.

Beyond that, I'd like to point out a general capability that might be helpful.  After making any plot, there are a lot of symbols that Ferret automatically defines that store information about the plot.  These are documented here,
ferret.pmel.noaa.gov/Ferret/documentation/users-guide/customizing-plots/SPECIAL-SYMBOLS

yes? [ commands to make the plot]

yes? show symbol *min
yes? show symbol *max

The symbols xaxis_min, xaxis_max show the endpoints of the X axis on the plot, and likewise yaxis_min and yaxis_max the y axis endpoints.  You could use these in a script to test whether your box lies within the boundaries of the script

go basemap x=100E:100E y=-90:90 20

let xpts = {-135,-140,-140,-135,-135}
let ypts = {-32,-32,-36,-36,-32}

let xpts_plus = 360+xpts

if `xpts[i=@max] LT ($xaxis_max) and xpts[i=@min] GT ($xaxis_min)` THEN
   plot/vs/over/nolab xpts, ypts
else
...

On 11/26/2012 12:57 PM, Luke M wrote:

Thanks Steve for the clarification... I was able to get it working now :)

     L.

On Mon, Nov 26, 2012 at 10:43 AM, Steve Hankin <steven.c.hankin@xxxxxxxx> wrote:

On 11/26/2012 12:29 PM, Luke M wrote:

Hi Steve & Sudeer

thank you for your feedback. Indeed, I am still trying to figure out the command for creating a simple location box on a map that goes around the Greenwich meridian.

Any thoughts on how to go about doing this?

The paragraph below suggests two methods that will work.  Suggestion "a" is simply to use the coordinate domain 20:380 when specifying the longitude limits of your box.

    - Steve

Thanks!

On Fri, Nov 23, 2012 at 2:28 PM, Steve Hankin <steven.c.hankin@xxxxxxxx> wrote:

Hi Luke,

First guess (w/out actually trying your commands) is that you are having an issue about the encoding of the dateline.  By default the GO fland script doesn't specify anything about the longitude branch point, so the longitude branch point is inherited from the underlying etopo data set.  That family of datasets, I believe, go round the earth from 20E(20) to 20E (380).   (To see this try the commands use etopo60; show grid rose)   So you either need to a) specify the longitude range of your box to be in the domain of 20:380 -- OR -- b) pre-set the longitude encoding of your base map by using argument 5 of fland.jnl.  Here is the output of
yes? go/help fland

! usage:       arg1        arg2        arg3          arg4      arg5      arg6
!  GO fland [resolution] [palette] [overlay_style] [detail] [x=lo:hi] [y=lo:hi]

! arg 1 - resolution - may be 120,60,40,20,10, or 5     default=20
!         To use resolution "nnn" the file etoponnn must exist.
! arg 2 - palette - may be any palette on your system.  Normally solid colors
!                   like black, gray,red, etc. (see Fpalette '*') default=gray
! arg 3 - overlay_style - "basemap", "transparent", or "overlay" (default)
! arg 4 - detailed - may be "detailed", "all" or "solid"  default=solid
!         Use "detailed" together with a spectrum like dark_terrestrial
!         Use "all" to plot oceans as well as land.
! arg 5 - longitude limits - specify as for any FERRET longitude range
! arg 6 - latitude  limits - specify as for any FERRET latitude  range

Hope this helps - Steve

==========================================================

On 11/23/2012 2:32 PM, Luke M wrote:

Hi everyone,

I'm trying to plot a simple box outline over a map to show the location of a particular area. Using Ferret v6.82, if I do the following command, I get a nice box outline over southern Australia:

set region x=100E:100E/y=-90:90
yes? go fland 20 white
go fland
plot/vs/over/nolab/line=10 {-135,-140,-140,-135,-135},{-32,-32,-36,-36,-32}


However, I am having difficulty trying to plot the following two boxes:

a. over the south-central Pacific Ocean (160W through 100W, and 40S to 20S)

b. over the British Isles (5W through 5E, and 45N through 60N)


Any suggestions on how I can do this?

Thanks!