<div dir="ltr"><div><div><div><div>From a 'science/statistics' point of view, once different structures [EOF patterns] are not "significantly different" from adjacent patterns, then you are looking at sampling issues.<br><br></div>Because atmosphere/ocean/geophysical data most-often have 'red' spectrums, the number of significant patterns rarely exceeds (say) 3 or 4 EOFs. <br><br></div>Likely, at EOF 30, almost every other grid point will be oscillating about the zero contour. Hence, **lots of contours**. From a science/statistics point of view they are uninterpretable. Well, except to say they are 'sampling noise.'<br><br>NCL has a function which will use North's 'rule-of-thumb' to assess EOF significance.<br><br><a href="http://www.ncl.ucar.edu/Document/Functions/Contributed/eofunc_north.shtml">http://www.ncl.ucar.edu/Document/Functions/Contributed/eofunc_north.shtml</a><br><br>==<br></div>Please see:<br><br><a href="http://www.ncl.ucar.edu/Applications/eof.shtml">http://www.ncl.ucar.edu/Applications/eof.shtml</a><br></div>Example 6<br><div><div><br></div><div>Cheers<br></div><div><br><br></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Feb 28, 2018 at 9:51 AM, Mary Haley <span dir="ltr"><<a href="mailto:haley@ucar.edu" target="_blank">haley@ucar.edu</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-size:small">Hi Tobias,</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">Thanks for providing the files. I just ran your script with both NCL V6.4.0 and our 6.5.0 development version and it didn't produce any errors.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">What kind of system are you running on? I ran this from a MacOS system.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">This kind of error seems to happen when you have small plots that have either lots of contours or very "twisty" contours. As you described, sometimes tweaking things slightly can make the problem go away.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">I don't know what you've tried so far, but here are some suggestions:</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">1) Use raster contours instead of smooth contours, by setting:</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">res@cnFillMode = "RasterFill"</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">This can sometimes make the plotting go faster, too. However, you will need to look to the contours to see if they are too blocky looking for your purpose. </div><br><div class="gmail_default" style="font-size:small;display:inline">2) Make</div> the <div class="gmail_default" style="font-size:small;display:inline">panel </div>plots slightly larger, as this gives NCL more room to draw the contours and hence less likely to run into contour drawing problems. The way to do this is by setting gsnPanelXWhiteSpacePercent and gsnPanelYWhiteSpacePercent to smaller numbers, like 1 or 2.<div><br></div><div><div class="gmail_default" style="font-size:small">If you find that the plots are getting too close in this case, then you might consider getting rid of the gsnLeftString title, since it's the same for every plot and you already have part of that title as the main title for the panel main string. You can then set the "exp var = x.xx" string as a gsnCenterString instead of a gsnRightString:</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small"><font face="monospace, monospace"> res@gsnLeftString = ""</font></div><div class="gmail_default" style="font-size:small"><font face="monospace, monospace"> do ii=10,19</font></div><font face="monospace, monospace">; <div class="gmail_default" style="font-size:small;display:inline"> </div>res@gsnRightString = "exp var = "+sprintf("%4.2f",eof@pcvar(ii<wbr>)) <br> <div class="gmail_default" style="font-size:small;display:inline"> </div> res@gsnCenterString = "exp var = "+sprintf("%4.2f",eof@pcvar(ii<wbr>))</font></div><div><font face="monospace, monospace"><div class="gmail_default" style="font-size:small;display:inline"> . . .</div><br></font><div class="gmail_default" style="font-size:small"><p class="m_-230834267374738986m_121849855172459341gmail-p1" style="margin:0px;font-style:normal;font-variant:normal;font-weight:normal;font-stretch:normal;font-size:18px;line-height:normal;color:rgb(52,163,39);background-color:rgb(255,255,255)"><span class="m_-230834267374738986m_121849855172459341gmail-s1" style="font-variant-ligatures:no-common-ligatures"><font face="monospace, monospace">
</font></span></p>
</div><div><div class="gmail_default" style="font-size:small"><font face="monospace, monospace"> end do</font></div><br></div><div><div class="gmail_default" style="font-size:small">3) If you can stand to have a non-equal number of plots per row, then draw the plots in a 4 x 3 configuration instead of a 2 x 5 configuration, which gives them more room. You can force the last plot to be left-justified by setting pres@gsnPanelCenter = False:</div><br><font face="monospace, monospace">pres@gsnPanelCenter = False<br>gsn_panel(wks,plot(0:9),(/4,3/<wbr>),pres)</font><br><br><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">If none of this helps, please write back to ncl-talk and let us know.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">[ I see that Rick just responded and said he could reproduce your error. I'll check with him about why my environment is different than his. ]</div><span class="HOEnZb"><font color="#888888"><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">--Mary</div><div class="gmail_default" style="font-size:small"><br></div><br></font></span></div></div></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="h5">On Wed, Feb 28, 2018 at 5:13 AM, Tobias Kleine <span dir="ltr"><<a href="mailto:tobias.kleine@gmx.net" target="_blank">tobias.kleine@gmx.net</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5">
<div bgcolor="#FFFFFF" text="#000000">
<font size="-2"><font face="Arial">Hi there,<br>
<br>
I am currently working on EOF analysis of SSTs in the North
Atlantic. While plotting the first 30 EOFs (polar plot) I for
the first time encountered the apparently infamous RPRAM -
ALGORITHM FAILURE error. I quickly found out that often enough
it has something to do with the contour intervals or levels and
thus played around with that for a while. But so far I've not
managed to plot all my 30 EOF patterns with one setting for the
contour levels and making all plots actually get drawn by ncl. <br>
<br>
I also found out, that the ARSCAM/ARPRAM bug has (according to
<a class="m_-230834267374738986m_-99884152706125811moz-txt-link-freetext" href="http://www.ncl.ucar.edu/prev_releases.shtml#ARSCAMARPRAMBugFixed5.2.1" target="_blank">http://www.ncl.ucar.edu/prev_r<wbr>eleases.shtml#ARSCAMARPRAMBugF<wbr>ixed5.2.1</a>)
been fixed with NCL5.2.1 . So I wondered my problem might be or
if this is the reemergence of it? <br>
<br>
I have uploaded my data file and the script to the incoming ftp
directory under the following names:<br>
<a href="http://predictor01_sst_oct.nc" target="_blank">predictor01_sst_oct.nc</a> (data, 50MB)<br>
SUPPORT_analyze_eof_sst.ncl (script, 4KB) <br>
<br>
-I am running ncl version 6.4.0<br>
-System type (don't 100% which part of this is relevant) Linux
mlogin105 2.6.32-696.18.7.el6.x86_64 #1 SMP Thu Dec 28 20:15:47
EST 2017 x86_64 x86_64 x86_64 GNU/Linux<br>
- error message: <br>
fatal:ContourPlotDraw: ARPRAM - ALGORITHM FAILURE<br>
fatal:ContourPlotDraw: ARPRAM - ALGORITHM FAILURE<br>
fatal:ContourPlotDraw: ARSCAM/ARPRAM - ALGORITHM FAILURE<br>
fatal:ContourPlotDraw: draw error<br>
fatal:ContourPlotDraw: draw error<br>
fatal:PlotManagerDraw: error in plot draw<br>
fatal:_NhlPlotManagerDraw: Draw error<br>
<br>
Thanks for considering to help me out on this issue.<br>
I hope I did not forget to submit relevant information.<br>
<br>
All the best<span class="m_-230834267374738986HOEnZb"><font color="#888888"><br>
Tobias Kleine<br>
Institut für Meereskunde<br>
Universität Hamburg, Germany<br>
<br>
<br>
</font></span></font></font>
</div>
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