<div dir="ltr">Olivier,<br>You'll probably want to use a combination of maskout() and <a href="http://www.iges.org/grads/gadoc/gradcomdsetstrmden.html">set strmden</a> to control the appearance of the arrowheads on a streamline plot. The maskout() function will plot a set of streamlines in an area corresponding to whatever speed, direction, or other threshold you want (sounds like you want to use speed as a threshold), and all of the streamlines plotted will correspond to the current 'set strmden' settings. Between each display command you will want to re-enter the 'set strmden' command with different settings and use different thresholds in the maskout() function.<br><br>Jeff Duda<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Oct 19, 2014 at 5:11 AM, Olivier TRECA <span dir="ltr"><<a href="mailto:otreca@me.com" target="_blank">otreca@me.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word">Hello,<div><br></div><div>My name is Olivier and I’m from France. I use GrADS to make the maps which describe the weather and the migration of the birds.</div><div><br></div><div>Could see my map on this site : </div><div><br></div><div><a href="http://www.chasseurdemigrateurs.com/meteo/view/2014/10/19" target="_blank">http://www.chasseurdemigrateurs.com/meteo/view/2014/10/19</a></div><div><br></div><div>The wind is important but I don’t have found how to make cute arrows and so I use the streamlines. But I’m not happy.</div><div><br></div><div>What I want to make is small arrows when the wind is light and big one filled for example in red when the wind is stronger. </div><div><br></div><div>I think it could be possible drawing a rectangle and a triangle at the right place and with the right size… but I’m not aware with this type of manipulation.</div><div><br></div><div>If somebody could help me !</div><div><br></div><div>Many thanks</div><div><br></div><div><span style="font-family:Georgia;text-align:-webkit-auto">Olivier TRECA</span></div><div><span style="border-collapse:separate;font-family:Georgia;border-spacing:0px"><div><a href="mailto:otreca@me.com" target="_blank">otreca@me.com</a></div><div><br></div></span><br><span><img src="cid:7205E93D-74A6-4D61-A6B4-6E7B65568125" height="160" width="200"></span>
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<br></blockquote></div><br><br clear="all"><br>-- <br>Jeff Duda<br>Graduate research assistant<br>University of Oklahoma School of Meteorology<br>Center for Analysis and Prediction of Storms<br>
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