display
command is how you actually display data (output
expressions) plots via the graphics output window. The command
is:
display expression
or
d expression
The simplest expression
is a variable abbreviation.
If you display when all dimensions are fixed, you get a single value which is typed out.
If you display when one dimension varies, you get a 1-D line graph by default.
If you display when two dimensions are varying, you get a 2-D contour plot by default.
A variety of plot types are available in addition to the above defaults.
GrADS will overlay the output from each display command. To clear the display, enter:
clear
(or just c
)
Issued without parameters, the clear
command does pretty heavy
duty clearing of many of the GrADS internal settings. Parameters
can be added to limit what is cleared when using more advanced
features, for example:
c events
flushes the events
buffer (e.g., mouse clicks)c graphics
clears the graphics, but not the
widgets c hbuff
clears
the display buffer when in double buffer modeWARNING: If you make any error in the syntax of clear then GrADS does the full clear...
Before you can display a graph of your data, you will need to set the type of plot you want and, probably, some other graphics parameters as well.
By default, when one dimension varies, you get a line graph, and when two dimensions vary, you get a contour plot. These defaults can be changed by the command:
set gxout graphics_type
Some examples of graphics_type
are contour,
shaded, grid, bar, vector,
or streamline
. For a
complete list, see the reference
page.
There are many options that can be set to control how the
data will be displayed for each graphics_type
.
For the graphics output types vector, stream,
and
barb
, the plotting routines need two result grids, where the
first result grid is treated as the U component, and the second result
grid is treated as the V component. These two result grids are
provided to the display command by
entering two expressions separated by a semicolon:
display u ; v
display ave(u,t=1,t=10) ; ave(v,t=1,t=10)
For the graphics output types vector
and
stream
, you can specify a third result grid that will be used to
colorize the vectors or streamlines:
display u ; v ; mag(u,v)
display u ; v ; hcurl(u,v)
For a graphics output type wxsym
, each value at a station
location is assumed to be a wx symbol code number. To see a chart of
all available wx symbols and their corresponding code numbers, run the
sample script wxsym.gs
.