<div dir="ltr"><div>If you have a PDEF line in your control file or the XDEF and YDEF lines have different numbers for dimension sizes than what is in the PDEF entry then GrADS will perform interpolation before plotting values, which is probably the cause of your slowdown. Your only hope is to not make GrADS perform the interpolation. I'm not sure if that is readily done. I would recommend performing interpolation outside of GrADS in general.</div><div><br></div><div>Jeff Duda<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Feb 12, 2021 at 11:02 AM Brian Gaze <<a href="mailto:brianw.gaze@googlemail.com">brianw.gaze@googlemail.com</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"><div dir="ltr"><div dir="ltr">Jeff,<br></div><div dir="ltr"><br></div><div>Thanks. Perhaps I didn't explain well. That is what I do at the moment, but if a script generates X number of charts for a region it seems to complete much more quickly if the grib file has been regridded for that region rather than constrained using set lat and set lon. Perhaps the overhead is in opening the bigger file?</div><div><br></div><div>Brian </div><div dir="ltr"><br></div><div dir="ltr"><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, 12 Feb 2021 at 17:05, <<a href="mailto:gradsusr-request@gradsusr.org" target="_blank">gradsusr-request@gradsusr.org</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">Send gradsusr mailing list submissions to<br>
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Today's Topics:<br>
<br>
1. Regrid or constrain grid dimensions after opening grib file?<br>
(Brian Gaze)<br>
2. Re: Regrid or constrain grid dimensions after opening grib<br>
file? (Jeff Duda)<br>
<br>
<br>
----------------------------------------------------------------------<br>
<br>
Message: 1<br>
Date: Fri, 12 Feb 2021 16:39:13 +0000<br>
From: Brian Gaze <<a href="mailto:brianw.gaze@googlemail.com" target="_blank">brianw.gaze@googlemail.com</a>><br>
To: <a href="mailto:gradsusr@gradsusr.org" target="_blank">gradsusr@gradsusr.org</a><br>
Subject: [gradsusr] Regrid or constrain grid dimensions after opening<br>
grib file?<br>
Message-ID:<br>
<CA+pnuaOwvxJa4MwLg6Y02tNooCK0S7gsadx8FExnFe=<a href="mailto:FkfOprA@mail.gmail.com" target="_blank">FkfOprA@mail.gmail.com</a>><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
Hi,<br>
<br>
I know it is relatively straightforward to define a new grid using wgrib2<br>
but I wondered whether it is possible to do something similar in GRaDS? So<br>
just storing the new grid temporarily in memory whilst the script is<br>
working on the file data, for example to generate charts for a smaller<br>
region than the original grid covers.<br>
<br>
Essentially I'm trying to optimize without going through the overhead of<br>
writing out a new file using wgrib2.<br>
<br>
Thanks<br>
<br>
Brian<br>
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Message: 2<br>
Date: Fri, 12 Feb 2021 09:49:20 -0700<br>
From: Jeff Duda <<a href="mailto:jeffduda319@gmail.com" target="_blank">jeffduda319@gmail.com</a>><br>
To: GrADS Users Forum <<a href="mailto:gradsusr@gradsusr.org" target="_blank">gradsusr@gradsusr.org</a>><br>
Subject: Re: [gradsusr] Regrid or constrain grid dimensions after<br>
opening grib file?<br>
Message-ID:<br>
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<br>
Yes. Restrict the dimension environment.<br>
<br>
'set lat [bounds]'<br>
'set lon [bounds]'<br>
'set t [bounds]'<br>
'set z [bounds]'<br>
<br>
'define field'<br>
<br>
(perform operations on field)<br>
<br>
On Fri, Feb 12, 2021 at 9:47 AM Brian Gaze <<a href="mailto:brianw.gaze@googlemail.com" target="_blank">brianw.gaze@googlemail.com</a>><br>
wrote:<br>
<br>
> Hi,<br>
><br>
> I know it is relatively straightforward to define a new grid using wgrib2<br>
> but I wondered whether it is possible to do something similar in GRaDS? So<br>
> just storing the new grid temporarily in memory whilst the script is<br>
> working on the file data, for example to generate charts for a smaller<br>
> region than the original grid covers.<br>
><br>
> Essentially I'm trying to optimize without going through the overhead of<br>
> writing out a new file using wgrib2.<br>
><br>
> Thanks<br>
><br>
> Brian<br>
><br>
> _______________________________________________<br>
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><br>
<br>
<br>
-- <br>
Jeff Duda, Research Scientist<br>
University of Colorado Boulder<br>
Cooperative Institute for Research in Environmental Sciences<br>
NOAA/OAR/ESRL/Global Systems Laboratory<br>
Boulder, CO<br>
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</blockquote></div><br clear="all"><br>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><font size="2"><span>Jeff Duda, Research Scientist</span></font></div><div dir="ltr"><font size="2"><span></span></font>University of Colorado Boulder</div><div dir="ltr"><font size="2"><span></span></font>Cooperative Institute for Research in Environmental Sciences</div><div dir="ltr">NOAA/OAR/ESRL/Global Systems Laboratory<br><font size="2"><span>
<span>Boulder, CO<br></span></span></font>
</div></div></div></div></div></div></div></div></div></div>