<div dir="ltr"><div class="gmail_default" style="font-size:small">Tabish,</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">One thing you can try is setting the options minlat, maxlat, minlon, and maxlon to a box area that encloses the area you are interested in checking against the shapefile.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">For example, let's say your shapeflle contains outlines of the United States, but your data is only over the state of New Mexico.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">The state of New Mexico is roughly enclosed in the area: 31.3 to 37.1 latitude, and -109.1 to -102.9 longitude.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">So, I might call the mask function with:</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style><div class="gmail_default" style="font-size:small"><font face="courier new, monospace"> opt = True</font></div><div class="gmail_default" style="font-size:small"><font face="courier new, monospace"> opt@debug = True</font></div><div class="gmail_default" style="font-size:small"><font face="courier new, monospace"> opt@shape_var = "NAME_1"</font></div><div class="gmail_default" style="font-size:small"><font face="courier new, monospace"> opt@shape_names = "New Mexico"</font></div><div class="gmail_default" style="font-size:small"><span style="font-family:'courier new',monospace"> opt@minlat = 31.3</span><br></div><div class="gmail_default" style="font-size:small"><span style="font-family:'courier new',monospace"> opt@maxlat = 37.1</span></div><div class="gmail_default" style="font-size:small"><span style="font-family:'courier new',monospace"> opt@minlon = -109.1</span></div><div class="gmail_default" style="font-size:small"><span style="font-family:'courier new',monospace"> opt@maxlon = -102.9</span></div><div class="gmail_default" style><div class="gmail_default" style="font-size:small"><font face="courier new, monospace"> hgt_mask = shapefile_mask_data(hgt,"USA_adm1.shp",opt)</font></div><div style="font-size:small"><font face="arial, helvetica, sans-serif"><br></font></div><div style="font-size:small"><font face="arial, helvetica, sans-serif">What happens, then, is that the masking function doesn't even bother calling gc_inout for any area that is outside of this box, and thus it should run a little faster.</font></div><div style="font-size:small"><font face="arial, helvetica, sans-serif"><br></font></div><div style="font-size:small"><font face="arial, helvetica, sans-serif">Example "shapefiles_11.ncl" uses this method to speed up the masking:</font></div><div style="font-size:small"><font face="arial, helvetica, sans-serif"><br></font></div><div style><font face="arial, helvetica, sans-serif" style><a href="http://www.ncl.ucar.edu/Applications/shapefiles.shtml#ex11">http://www.ncl.ucar.edu/Applications/shapefiles.shtml#ex11</a><br></font></div><div style><font face="arial, helvetica, sans-serif" style><br></font></div><div style="font-size:small"><font face="arial, helvetica, sans-serif">--Mary</font></div><div style="font-size:small"><font face="courier new, monospace"><br></font></div></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Oct 15, 2014 at 6:26 AM, Dennis Shea <span dir="ltr"><<a href="mailto:shea@ucar.edu" target="_blank">shea@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><div><div><div>[1] shapefile_mask_data.ncl uses gc_inout which can be slow.<br><br></div>[2] You should create a (say) netCDF file which contains a masked variable.<br></div><div> This should be saved and used in all subsequent applications.<br></div><div> *This need be done only once.*<br></div><div><br></div>[3] Then use this variable (read from netCDF file) and then use NCL's mask function<br></div> on all subsequent applications.<br><br> <a href="https://www.ncl.ucar.edu/Document/Functions/Built-in/mask.shtml" target="_blank">https://www.ncl.ucar.edu/Document/Functions/Built-in/mask.shtml</a><br><br></div>Reply only to ncl-talk. No personal salutation.<br></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="h5">On Tue, Oct 14, 2014 at 3:03 PM, Tabish Ansari <span dir="ltr"><<a href="mailto:tabishumaransari@gmail.com" target="_blank">tabishumaransari@gmail.com</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 dir="ltr"><div class="gmail_default" style="font-family:verdana,sans-serif;color:#45818e">Hi</div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#45818e"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#45818e">I have a script wherein I read-in some data from an ascii file and then mask it on the basis of a shapefile by calling the script "shapefile_mask_data.ncl" within my script. My data has approximately 530x980 data points.</div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#45818e"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#45818e">Currently it takes around 2 hrs 10 minutes to finish the job. I have to repeat this process several times. In future I may have to even do this masking within a loop, which will make it impractical due to its inefficiency.</div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#45818e"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#45818e">Is there a way to speed up this process?</div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#45818e"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#45818e">Thanks in advance!</div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#45818e"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif;color:#45818e"><br></div><div><div dir="ltr"><font color="#3d85c6" face="trebuchet ms, sans-serif">Tabish U Ansari</font><div><font color="#3d85c6" face="trebuchet ms, sans-serif">MS Research Scholar<br>Environmental & Water Resources Engineering Division</font></div><div><font color="#3d85c6" face="trebuchet ms, sans-serif">Department of Civil Engineering</font></div><div><font color="#3d85c6" face="trebuchet ms, sans-serif">IIT Madras</font></div></div></div>
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