<!--Copyright (C) 1988-2005 by the Institute of Global Environment and Society (IGES). See file COPYRIGHT for more information.--> <html> <head> <title>Displaying Data in GrADS</title> </head> <body bgcolor="e0f0ff" text="#000000"> <a href="#DDP">Drawing Data Plots</a><br> <a href="#CTD">Clearing the Display</a><br> <a href="#GOT">Graphics Output Types</a><br> <a href="advdisplay.html">Advanced Display Options</a><br> <p> <hr> <a name="DDP"><h2>Drawing Data Plots</h2></a> The <code>display</code> command is how you actually display data (output expressions) plots via the graphics output window. The command is:<p> <dd><code><a href="gradcomddisplay.html">display</a> <i>expression</i></code><p> or<p> <dd><code>d <i>expression</i></code><p> The simplest <code><i>expression</i></code> is a variable abbreviation.<p> If you display when <b>all</b> dimensions are fixed, you get a <b>single</b> value which is typed out.<p> If you display when <b>one</b> dimension varies, you get a <b>1-D line graph</b> by default.<p> If you display when <b>two</b> dimensions are varying, you get a <b>2-D contour plot</b> by default.<p> A variety of <a href="#GOT">plot types</a> are available in addition to the above defaults.<p> <a name="CTD"><h2>Clearing the Display</h2></a><p> GrADS will overlay the output from each display command. To clear the display, enter:<p> <dd><code><a href="gradcomdclear.html">clear</a></code> (or just <code>c</code>)<p> Issued without parameters, the <code>clear</code> 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:<p> <ul> <code>c events</code> flushes the events buffer (e.g., mouse clicks)<br> <code>c graphics</code> clears the graphics, but <b>not</b> the widgets <br> <code>c hbuff</code> clears the display buffer when in double buffer mode</ul><p> WARNING: If you make any error in the syntax of clear then GrADS does the full clear...<p> <a name="GOT"><h2>Graphics Output Types</h2></a> <p> 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. <p> 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: <p> <ul> <code> <a href="gradcomdsetgxout.html">set gxout</a> <i>graphics_type</i> </code> </ul> <p> Some examples of <code><i>graphics_type</i></code> are <code>contour, shaded, grid, bar, vector,</code> or <code>streamline</code>. For a complete list, see the <a href="gradcomdsetgxout.html">reference page</a>. <p> There are many options that can be set to control how the data will be displayed for each <code><i>graphics_type</i></code>. <p> For the graphics output types <code>vector, stream,</code> and <code>barb</code>, 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 <a href="gradcomddisplay.html">display</a> command by entering two expressions separated by a semicolon: <p> <ul> <code> display u ; v<br> display ave(u,t=1,t=10) ; ave(v,t=1,t=10)<br> </code> </ul> <p> For the graphics output types <code>vector</code> and <code>stream</code>, you can specify a third result grid that will be used to colorize the vectors or streamlines: <p> <ul> <code> display u ; v ; mag(u,v)<br> display u ; v ; hcurl(u,v)<br> </code> </ul> <p> For a graphics output type <code>wxsym</code>, 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 <code>wxsym.gs</code>. </body> </html>
