<div dir="ltr"><div class="gmail_default" style="font-size:small">Hi Sri,</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">I'm not an expert on what colors to use to best fit your data, as it really depends from person to person what you are trying to accomplish.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">You have the right idea by explicitly setting your own color levels and then choosing individual colors to go with each level. </div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">One way you can make some colors stand out more than others is by using an RGBA array to define your colors, and then you can control the opacity of each color. I've attached an example script and the panel image where the last few colors are made more transparent, causing the lower contours to stand out more.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">Another method is if you are trying to avoid color maps with green in them, then go to our color table gallery:</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default"><a href="http://www.ncl.ucar.edu/Document/Graphics/color_table_gallery.shtml">http://www.ncl.ucar.edu/Document/Graphics/color_table_gallery.shtml</a><br></div><div class="gmail_default"><br></div><div class="gmail_default">and browse the various color maps. You could look at some of the smaller color maps because then you can pick out colors that you like and don't like. Each of these color maps has an RGB file associated with it, so you could also pick out the RGB colors that you like and mix and match RGB triplets. </div><div class="gmail_default"><br></div><div class="gmail_default">For example, if you look at the "lithology" color table:</div><div class="gmail_default"><br></div><div class="gmail_default"><a href="http://www.ncl.ucar.edu/Document/Graphics/ColorTables/lithology.shtml">http://www.ncl.ucar.edu/Document/Graphics/ColorTables/lithology.shtml</a><br></div><div class="gmail_default"><br></div><div class="gmail_default">and click on the "lithology.rgb" link you will see the RGB triplets. You can then select the colors you like and get the RGB value for that color. You can then set the color contours with:</div><div class="gmail_default"><br></div><div class="gmail_default"> res@cnFillPalette = (/ (/253,244,63/),(/224,197,158/),(/191,167,67/),(/184,234,295/)/) / 255.</div><div class="gmail_default"><br></div><div class="gmail_default">Notice that you need to divide by 255 to get values from 0 to 1.</div><div class="gmail_default"><br></div><div class="gmail_default">As a debugging tool, use "draw_color_palette" to draw a set of colors if you want to see what they look like. You can then tweak them as necessary.</div><div class="gmail_default"><br></div><div class="gmail_default">For example:</div><div class="gmail_default"><br></div><div class="gmail_default"><div class="gmail_default"> wks = gsn_open_wks("x11","rgb")</div><div class="gmail_default"><br></div><div class="gmail_default"> colors = (/(/253,244,63/), \</div><div class="gmail_default"> (/224,197,158/), \</div><div class="gmail_default"> (/191,167,67/), \</div><div class="gmail_default"> (/232,28,0/), \</div><div class="gmail_default"> (/110,73,9/), \</div><div class="gmail_default"> (/107,195,255/), \</div><div class="gmail_default"> (/129,3,255/)/) / 255.</div><div class="gmail_default"><br></div><div class="gmail_default"> draw_color_palette(wks,colors,False)</div><div class="gmail_default"><br></div><div class="gmail_default">creates the attached "rgb.000001.png" file. I've attached a "draw_my_colors.ncl" script that shows how to also draw the RGBA colors with transparency applied.<br></div><div class="gmail_default"><br></div><div class="gmail_default">I know this doesn't directly answer your question about what colors to use, but hopefully this gives you an idea of various methods you can use for selecting colors and tweaking them.</div><div class="gmail_default"><br></div><div class="gmail_default">--Mary</div><div class="gmail_default"><br></div></div><div class="gmail_default"><br></div><div class="gmail_default"><br></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Aug 17, 2018 at 7:48 AM, Sri Nandini <span dir="ltr"><<a href="mailto:snandini@marum.de" target="_blank">snandini@marum.de</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>On Aug 17, 2018 3:45:01 PM, Sri Nandini wrote:
<br><blockquote class="m_-3123593217311949864felamimail-body-blockquote"><div>Hello</div><div><br></div><div>I am plotting a simple mean evaporation panel plot with extreme values. As such i decided to use a non linear color scale for this to try to focus on the smaller changes and use white to "mask" the larger variability because that's not important and i want the reader to focus on the smaller changes.</div><div><br></div><div>But i cannot seem to really distribute a good color scheme to highlight the smaller changes reasonably and i am trying to not use green. I think it becomes clearer once you view the attached plot. I have attached the plotting resources used in my script below.<br></div><div>I have tried to change the ExplicitLevels values many times as well as the ;res@cnFillPalette = (/"Snow","Black","Blue","<wbr>PaleTurquoise","PaleGreen","<wbr>SeaGreen3" ,"Yellow","Pink","Red","<wbr>Orange","Brown"/) colors = (/"white", "black", "PeachPuff", "MintCream", "SlateBlue", \<br> ; "Khaki", "OliveDrab","BurlyWood", "LightSalmon", "Coral", \<br> ; "HotPink", "LemonChiffon", "AliceBlue", "LightGrey", \<br> ; "MediumTurquoise", "DarkSeaGreen", "Peru", "Tomato", \<br> ; "Orchid","PapayaWhip"/)</div><div><br></div><div>I would b grateful for any advice on selecting a colormap for extreme values.</div><div><br></div><div><br>;=============================<wbr>==============================<wbr>=======<br>;Here is a section of my code that draws a color fill plot<br>;=============================<wbr>==============================<wbr>========<br><br> wks = gsn_open_wks("pdf","all_<wbr>Evaporation_diff1")</div><div> gsn_define_colormap(wks,"<wbr>prcp_1")<br><br> res = True<br><br> res@cnFillOn = True ; turn on color<br> ;res@gsnSpreadColors = True ; use full colormap<br><br> res@cnLinesOn = False ; turn off contour lines<br> res@cnLevelSelectionMode = "ExplicitLevels" ; set manual contour levels<br> res@cnLevels = (/-1.5,-1.,-0.6,-0.4,-0.3,-0.<wbr>2,-0.1,0,0.1,0.2,0.3,0.4,0.5/)<wbr> ; set levels<br><br> ;res@cnFillPalette =(/"Snow"/)</div><div><br></div><div>;res@cnFillPalette =(/"Snow","Black","Blue", "DarkSeaGreen","PaleTurquoise"<wbr>,"PaleGreen","SeaGreen3" ,"OliveDrab","Snow","Snow","<wbr>BurlyWood","Pink","Salmon","<wbr>Orange","Red"/)<br><br> ;res@cnLevels = (/ -3,-1.,-0.5,-0.4,-0.3,-0.2,-0.<wbr>1,0.1,0.2,0.3,0.4,0.5,1.,3./) <wbr> ; set levels<br> ;res@cnLevels = (/ -4,-1.5,-1.,-0.5,-0.4,-0.3,-0.<wbr>2,-0.1,0.1,0.2,0.3,0.4,0.5,1./<wbr>) ; set levels<br> <br> res@gsnDraw = False ; Do not draw plot<br> res@gsnFrame = False ; Do not advance frome<br> res@lbLabelBarOn = False ; turn off individual label bars<br> res@tiMainString = " "<br> ;res@tiMainOffsetYF = 0.02 ; Move title up a little<br> res@gsnCenterString = " "<br> res@gsnLeftString = " "<br> res@gsnRightString = " "<br> res@cnRasterModeOn = True ; Raster mode shows grid cells<br> ;gsn_reverse_colormap(wks) <br><br> minlat = 30. ; min lat to mask<br> maxlat = 80. ; max lat to mask<br> minlon = -10. ; min lon to mask<br> maxlon = 100. ; max lon to mask<br><br> res@mpProjection = "LambertConformal" ; choose projection<br><br>;---masked plot<br> res@gsnAddCyclic = True ; regional plot<br><br> res@mpMinLatF = minlat ; min lat to mask<br> res@mpMaxLatF = maxlat ; max lat to mask<br> res@mpMinLonF = minlon ; min lon to mask<br> res@mpMaxLonF = maxlon ; max lon to mask<br><br></div></blockquote><br></div>
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