<div dir="ltr"><div>You have 4 categories [classifications; seasons].</div><div><br></div><div>I agree with Will's suggestion to use "RasterFill. <br></div><div>A general approach for categorical data:<br></div><div><br></div><div>See: <a href="http://www.ncl.ucar.edu/Applications/classification.shtml" target="_blank"><b>http://www.ncl.ucar.edu/Applications/classification.shtml</b></a></div><div><br></div><div>One example is 'kinda' like what you want: hdf4eos_5.ncl</div><div><pre> res = True ; plot mods desired
res@gsnMaximize = True
res@gsnAddCyclic = False
res@cnFillOn = True ; color fill
res@cnFillMode = "RasterFill" ; Raster Mode
res@cnLinesOn = False ; Turn off contour lines
<br>;;res@cnLevelSelectionMode = "ExplicitLevels" ; set explicit contour levels
;;res@cnLevels = ispan(1,3,1) ; one less than needed<br> res@cnLevelSelectionMode = "ManualLevels" ; set manual contour levels
res@cnMinLevelValF = 1 ; set min contour level
res@cnMaxLevelValF = 3 ; one less than max
res@cnLevelSpacingF = 1 ; set contour spacing
<br> colors = (/"blue" \ ; DJF
,"red" \ ; MAM
,"green" \ ; JJA
,"yellow" /) ; SON
res@cnFillPalette = colors ; set color map
<br> res@lbLabelPosition = "Center" ; label position
res@lbLabelAlignment = "BoxCenters" ; label orientation
res@lbLabelStrings = (/"DJF","MAM","JJA","SON"/)<br><br>=======================<br>If slow:
res@trGridType = "TriangularMesh" ; *faster* graphic rendering
<br> ====
</pre></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, Oct 31, 2019 at 6:56 PM Will Hobbs via ncl-talk <<a href="mailto:ncl-talk@ucar.edu" target="_blank">ncl-talk@ucar.edu</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal">Hi Lesley<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Sorry, can’t point you to a detailed explanation, but the default contouring mode is ‘AreaFill’, and there is a bit of a description under the ‘cnFillMode’ resource help entry.<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Have you tried setting cnFillMode = “RasterFill”, with the same explicit levels? I suspect it will ‘digitise’ the filling in the way that you want (but I don’t know).<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Will<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<div style="border-color:rgb(181,196,223) currentcolor currentcolor;border-style:solid none none;border-width:1pt medium medium;padding:3pt 0cm 0cm">
<p class="MsoNormal"><b><span style="font-size:12pt;color:black">From: </span></b><span style="font-size:12pt;color:black">ncl-talk <<a href="mailto:ncl-talk-bounces@ucar.edu" target="_blank">ncl-talk-bounces@ucar.edu</a>> on behalf of Lesley Smith - NOAA Affiliate via ncl-talk <<a href="mailto:ncl-talk@ucar.edu" target="_blank">ncl-talk@ucar.edu</a>><br>
<b>Reply-To: </b>Lesley Smith - NOAA Affiliate <<a href="mailto:lesley.l.smith@noaa.gov" target="_blank">lesley.l.smith@noaa.gov</a>><br>
<b>Date: </b>Friday, 1 November 2019 at 11:49 AM<br>
<b>To: </b>ncl-talk <<a href="mailto:ncl-talk@ucar.edu" target="_blank">ncl-talk@ucar.edu</a>><br>
<b>Subject: </b>[ncl-talk] how does interpolation work in contour plot?<u></u><u></u></span></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Hi ncl-talk, <u></u><u></u></p>
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<p class="MsoNormal">I'm trying to plot the season of the year with maximum precipitation<u></u><u></u></p>
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<p class="MsoNormal">for each grid-point in the U.S.<u></u><u></u></p>
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<p class="MsoNormal">I created a matrix of output, dimensioned lat x lon.<u></u><u></u></p>
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<p class="MsoNormal">There are only 4 possible (integer)values: 1,2,3,4 <--which I checked.<u></u><u></u></p>
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<p class="MsoNormal">(1 is DJF, 2 is MAM, etc. I'll make this pretty later.) <u></u><u></u></p>
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<p class="MsoNormal">I get the attached plot, cam1x1_maxx_doy_precip.r01.1901.jpg,<u></u><u></u></p>
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<p class="MsoNormal">(which I hope you can see) which I believe is correct.<u></u><u></u></p>
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<p class="MsoNormal">However, I do not understand why there appear to be so many floats<u></u><u></u></p>
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<p class="MsoNormal">in the plot. Is there some kind of interpolation going on?<u></u><u></u></p>
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<p class="MsoNormal">When I try to set the contour levels explicitly, 1,2,3,4 I do<u></u><u></u></p>
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<p class="MsoNormal">not seem to get a correct result.<u></u><u></u></p>
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<p class="MsoNormal">Thus, it would be awesome if someone could point me to <u></u><u></u></p>
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<p class="MsoNormal">a page explaining interpolation in contour plots.<u></u><u></u></p>
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<p class="MsoNormal">Thanks very much!<u></u><u></u></p>
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<p class="MsoNormal">-Lesley Smith<u></u><u></u></p>
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