en Copyright 1997-2015, David W. Fanning david@idlcoyote.com (David Fanning) Wed, 04 Mar 2015 14:51:39 GMT david@idlcoyote.com (David Fanning) http://www.idlcoyote.com/index.html IDL Programming Tips and Examples http://www.idlcoyote.com/index.html http://www.idlcoyote.com/coyote_tile.jpg http://www.idlcoyote.com/programs/cgps_open.pro I fixed a problem in cgPS_Open that prevented the PostScript device from using hardware fonts once it had been set to use True-Type fonts, if the properties of cgPS_Open were being set with cgControl. I don't think too many people would have run into this bug. article 1085 at idlcoyote.com Wed, 04 Mar 2015 14:51:39 GMT http://www.idlcoyote.com/programs/cgcolor.pro I have been getting reports that Mac computers are now reporting inaccurate draw widget sizes (similar to Windows computers). So, I changed the algorithm for picking the "opposite" or "background" color in cgColor. Previously, I read the color from an open graphics window. Now, I only do that if you ask for the "OPPOSITE" or "BACKGROUND" color. Otherwise, I assume the background color is "white". If you do ask for the color, I read the open graphics window at a location 5 pixels removed from what is "supposed" to be the upper-right corner of the window (often reported incorrectly). If I have any problems reading this pixel, I report the background color as "white". article 1084 at idlcoyote.com Mon, 02 Mar 2015 14:23:48 GMT http://www.idlcoyote.com/programs/cgdrawvectors.pro I complete rewrote the cgDrawVectors program over the weekend to match the output of the NASA Astronomy Library program PartVelVec. It works in all my tests, include on map projections set up with Map_Set (via cgMap_Set) and Map_Proj_Init (via cgMap). The key new feature is that the programs correctly scales the vector components according to the scale of the plot. On maps, the vector components are always scaled by the aspect ratio 180./360. This depends on getting a new version of cgArrow, too. article 1083 at idlcoyote.com Tue, 24 Feb 2015 14:28:30 GMT http://www.idlcoyote.com/programs/cgarrow.pro The cgArrow program was updated this morning to allow the user to specify a vector of colors with which to draw the arrows. The code was also changed to bring the program closer to the machine, so that arrows are now drawn much faster than before. This is especially important when drawing many arrows with programs like cgDrawVectors. article 1082 at idlcoyote.com Tue, 24 Feb 2015 14:28:30 GMT http://www.idlcoyote.com/programs/cggooglemapwidget__define.pro The Google map interface allows latitude and longitudes to be specified with up to six decimal points of accuracy. I had been using 4. I've upped it to all six this morning. article 1081 at idlcoyote.com Thu, 19 Feb 2015 17:14:23 GMT http://www.idlcoyote.com/programs/cgmap__define.pro There was a typo in the cgMap object that prevented the ASPECT keyword from working properly. Corrected this morning. article 1080 at idlcoyote.com Thu, 19 Feb 2015 17:14:23 GMT http://www.idlcoyote.com/programs/cgdrawvectors.pro There has been a significant update to the cgDrawVectors program this morning. A user complained that the vectors drawn with the program did not match those of the NASA Astronomy Library routine PartVelVec. For regular plots, cgDrawVectors and PartVelVec produce essentially identical plots now. I think cgDrawVectors is slightly better for producing vector fields on map projections, however. This is probably due to the reliance on Map_Proj_**** routines for calculating vector endpoints. PartVelVec doesn't do anything special for map projections. article 1079 at idlcoyote.com Thu, 19 Feb 2015 17:14:23 GMT http://www.idlcoyote.com/programs/cgtaylordiagram.pro I updated the cgTaylorDiagram program today. There was a problem when drawing multiple Taylor plots to a PostScript file, in that a cgDisplay command in the file was redefining the PostScript "window" size. I am now bypassing this command when in the PostScript device. article 1078 at idlcoyote.com Thu, 19 Feb 2015 17:14:23 GMT http://www.idlcoyote.com/misc_tips/coyote_retires.php Coyote announces retirement, effective end of November, 2014. Thank you to everyone who has made my 26 year involvement with IDL the most gratifying and wonderful career I could have imagined. It was an honor and privilege to learn something new about IDL almost every day with you. I will miss all of you more than you can imagine. article 1077 at idlcoyote.com Thu, 27 Nov 2014 14:59:04 GMT http://www.idlcoyote.com/programs/zip_files/coyoteprograms.zip There was an update to the Coyote Library today that involved updates to such popular programs as cgPlot, cgContour, and cgLayout. article 1077 at idlcoyote.com Thu, 27 Nov 2014 14:59:04 GMT http://www.idlcoyote.com/programs/cgdrawvectors.pro A problem with plotting wind vectors on map projections with cgDrawVectors was brought to my attention this weekend. Indeed, the vectors were pointing in the wrong direction. This was a tough nut to crack, but I believe the program works correctly now. article 1075 at idlcoyote.com Sun, 02 Nov 2014 17:34:22 GMT http://www.idlcoyote.com/ng_tips/dictbug.php A dictionary dereference bug crashes IDL 8.3 and 8.4 on Windows machines. The problem doesn't occur on UNIX machines, but the Windows work-around throws an error on UNIX machines. Sigh... This bug is on the Critical Bug list at ExelisVIS. article 1074 at idlcoyote.com Sun, 02 Nov 2014 17:34:22 GMT http://www.idlcoyote.com/programs/cgwindrose.pro I updated cgWindRose today to allow multiple wind rose plots to be displayed in the same graphics window. Some of the default behavior of the program changed to accommodate multiple plots. article 1073 at idlcoyote.com Thu, 23 Oct 2014 13:40:51 GMT http://www.idlcoyote.com/misc_tips/idlblog.php The IDL Data Point blog is obfuscated behind firewalls on the ExelisVIS web site. Here is how to find it with Feedly. article 1072 at idlcoyote.com Thu, 23 Oct 2014 10:16:00 GMT http://www.idlcoyote.com/math_tips/negzero.php This article describes when zero is less than a negative number in IDL and why it might matter to you. article 1071 at idlcoyote.com Tue, 21 Oct 2014 13:30:23 GMT http://www.idlcoyote.com/fileio_tips/caldata.php Everyone, including me, seems to be confused by the time or calendar data format. After looking into it this morning, I found it surprisingly easy to use. This article explains how to use it to read and write calendar data in a file. article 1070 at idlcoyote.com Fri, 17 Oct 2014 18:09:40 GMT http://www.idlcoyote.com/programs/cgplots.pro I updated cgPlotS this morning to allow a vector of different symbols to be passed via the PSYM keyword. article 1069 at idlcoyote.com Fri, 10 Oct 2014 16:33:39 GMT http://www.idlcoyote.com/programs/cggeomap.pro I updated cgGeoMap this morning to read geoTiff files that use a ModelTransformationTag field to specify the pixel scale and corner tie point, instead of the more common ModelPixelScaleTag and ModelTiePointTag fields. article 1068 at idlcoyote.com Fri, 10 Oct 2014 16:33:39 GMT http://www.idlcoyote.com/programs/cgplots.pro I updated cgPlotS this morning to allow a vector of different symbols to be passed via the PSYM keyword. article 1067 at idlcoyote.com Fri, 10 Oct 2014 16:33:39 GMT http://www.idlcoyote.com/cg_tips/histoalign.php This article describes the keywords that need to be used with cgHistoplot to align overlapping histogram plots perfectly. article 1066 at idlcoyote.com Thu, 09 Oct 2014 19:06:22 GMT http://www.idlcoyote.com/programs/zip_files/coyoteprograms.zip I added error bar functionality to the plots in cgZPlot, the zoomable, resizeable graphics window. This will require a Coyote Library update, as several programs changed to make this possible. article 1065 at idlcoyote.com Tue, 30 Sep 2014 18:06:28 GMT http://www.idlcoyote.com/ps_tips/allgreek.php A bug in the IDL 8.3 direct graphics PostScript driver will cause you to think your PostScript device speaks Greek. Here are a couple of ways to work around the bug. article 1064 at idlcoyote.com Mon, 29 Sep 2014 17:13:16 GMT http://rawahranger.com/2014/09/hiking-colorado-trail/ In August, 2014, Coyote hiked the 500-mile Colorado Trail from Denver to Durango. Here is a short account of his adventure. article 1063 at idlcoyote.com Mon, 29 Sep 2014 17:13:16 GMT http://www.idlcoyote.com/graphics_tips/vectors.html I've written a new vector plotting program, cgVelocityVectors, today in the manner of the NASA Astronomy Library routine PartVelVec. I had a couple of objectives in mind. First, I wanted an easier way to make a vector length key so users could easily match the length of a vector to its magnitude. Second, I wanted to add a couple of features to the program to make the vectors more attractive. For example, I wanted to be able to draw vectors with solid arrow heads. article 1062 at idlcoyote.com Sat, 22 Mar 2014 20:23:36 GMT http://www.idlcoyote.com/cg_tips/webexhelp.php Coyote is offering a free on-line course, entitled Installing and Using the Coyote Graphics System, on Thursday, March 13. See the announcement for details. The course is primarily for users who want help installing the Coyote Graphics Library and using it effectively. article 1061 at idlcoyote.com Sat, 08 Mar 2014 19:41:34 GMT http://www.idlcoyote.com/gallery/index.html#LINEAR_TREND_PLOT I realized the Linear Trend Plot I put up a couple of days ago had some problems with polygon overlap at the crossings, but I didn't have time to work on solving the problem right then. Reader Kang Wang, however, went to work on the problem and solved it in an elegant way. I have implemented his solution and put the updated code in the Coyote Plot Gallery today. article 1060 at idlcoyote.com Sat, 08 Mar 2014 18:37:58 GMT http://www.idlcoyote.com/gallery/index.html Matthew Argell has taken on a project to learn the new function graphics routines. To do so, he is trying to replicate the plots in the Coyote Plot Gallery. Neither Matthew nor I are function graphics experts, so there is no guarantee we are writing the programs in the most efficient or best way. Indeed, about half the programs Matthew has sent me so far haven't run on my machine. Sometimes it takes me hours to figure out how to get them to work. However, if I get them to run, I post them to the Gallery. Depending upon which version of IDL you have, I expect your mileage will vary, too. article 1059 at idlcoyote.com Sat, 08 Mar 2014 18:37:58 GMT http://www.idlcoyote.com/graphics_tips/misscont.php Your missing contour data doesn't look, well, missing in filled contour plots? Here is a new article that explains how easy it is to make missing data look like its missing. article 1058 at idlcoyote.com Sat, 15 Feb 2014 16:55:53 GMT http://www.idlcoyote.com/ps_tips/psdefsize.php Someone asked me this morning how to create a PostScript file of a specific size using my Coyote Graphics routines. Before I knew it, a dozen programs had blown up, I had shrapnel everywhere, and it took me most of the day to set things right. But, I had an answer. I just didn't realize it was going to take six hours to get it! Anyway, I wrote an article so I don't have to do that again! You should take a moment to update your Coyote Library, too. article 1057 at idlcoyote.com Tue, 11 Feb 2014 16:49:45 GMT