Re: [ferret_users] aspect ratio

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

Hi David -

Do this using DEF VI/AXES.

Suppose I want 4 windows that are 40 degrees (longitude) wide and 30  
degrees (latitude) high in a 2by2 viewport window. Thinking of  
everything in degrees, I want 5 degrees space on the bottom, 4  
degrees space between them vertically, and 8 degrees on top for the  
label. I want 6 degrees on the left, 5 degrees in the middle  
horizontally, and 7 degrees on the right for the colorbar.

! the viewport width/height (degrees)
let wide=40;let ht=30
! spacing in the vertical direction. totht is the entire plot height  
(degrees).
let bot=5; let vmid=4; let top=8; let totht=`bot+vmid+top+2*ht`
! spacing in the horizontal direction. totwidth is the entire plot  
width (degrees)
let left=6; let hmid=5; let right=7; let totwidth=`left+hmid+right 
+2*wide`
! use these values to set the window aspect ratio
set win/asp = `totht/totwidth`
! define the viewports using the above values
def vi/axes/xli=`left/totwidth`,`(left+wide)/totwidth`/yli=`bot/ 
totht`,`(bot+ht)/totht` botleft
def vi/axes/xli=`left/totwidth`,`(left+wide)/totwidth`/yli=`(bot+vmid 
+ht)/totht`,`(bot+vmid+2*ht)/totht` topleft
def vi/axes/xli=`(left+wide+hmid)/totwidth`,`(left+hmid+2*wide)/ 
totwidth`/yli=`bot/totht`,`(bot+ht)/totht` botright
def vi/axes/xli=`(left+wide+hmid)/totwidth`,`(left+hmid+2*wide)/ 
totwidth`/yli=`(bot+vmid+ht)/totht`,`(bot+vmid+2*ht)/totht` topright

In general the idea is to think of everything in user units when  
trying to make a plot with the correct aspect ratio (as for vectors  
on a map).

Billy K

On Jan 21, 2006, at 9:13 AM, David Wang wrote:

> Hello Ferreters,
>
> how can i get the aspect ratio (geometric or geographic) of each
> plotting region (not viewpoint itself) in a multi-viewpoint window? my
> purpose is to adjust the direction of velocity vectors propotional to
> the scaling of plotting area. any thoughts?
>
> thanks very much,
> - d.
>
> --
> Daiwei (David) WANG    Graduate Student
> Dept. of Earth and Environmental Sciences and
> Lamont-Doherty Earth Observatory
> Columbia University
> Email: dwang<AT>ldeo.columbia.edu