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<p class="MsoNormal">Hi Vero,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thank you for your response. The only issue I have running the EOF in R is the data size.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">My raster stack is a MODIS time series. <o:p></o:p></p>
<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">> stk<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">class : RasterStack <o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">dimensions : 2423, 2470, 5984810, 690 (nrow, ncol, ncell, nlayers)<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">resolution : 499.9339, 499.9718 (x, y)<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">extent : -85163.44, 1149673, 5656775, 6868207 (xmin, xmax, ymin, ymax)<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">coord. ref. : NA <o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">names : X2001.01.01, X2001.01.09, X2001.01.17, X2001.01.25, X2001.02.02, X2001.02.10, X2001.02.18, X2001.02.26, X2001.03.06, X2001.03.14, X2001.03.22, X2001.03.30,
X2001.04.07, X2001.04.15, X2001.04.23, ... <o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">min values : 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, ... <o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">max values : 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100, 100,
100, 100, 100, ...<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-size:12.0pt;color:black">The size of raster stack is ~8 mb.
<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">>object.size(stk)<o:p></o:p></span></p>
<p class="MsoNormal" style="background:white"><span style="font-size:12.0pt;color:black">8699416 bytes<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">But, when I try to export it to a table, it becomes several GBs, which is too much for my desktop. (Though, my desktop has ~32 GB RAM with 8 cores)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Therefore, I am looking for the possibility of running i.pca but on transposed raster time series stack.
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I am motivated by the nice grasswiki on PCA which compares the i.pca outputs against the R equivalent functions.<o:p></o:p></p>
<p class="MsoNormal"><a href="https://grasswiki.osgeo.org/wiki/Principal_Components_Analysis">https://grasswiki.osgeo.org/wiki/Principal_Components_Analysis</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I would appreciate any help on this.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Cheers,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Shiva<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><b>From:</b> Veronica Andreo <veroandreo@gmail.com> <br>
<b>Sent:</b> Friday, July 13, 2018 1:40 AM<br>
<b>To:</b> shiva_khanal@hotmail.com<br>
<b>Cc:</b> grass-user <grass-user@lists.osgeo.org><br>
<b>Subject:</b> Re: [GRASS-user] About Spatial PCA in GRASS<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt">Hi Shiva,<o:p></o:p></p>
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<p class="MsoNormal">El jue., 12 jul. 2018 a las 2:45, Shiva Khanal (<<a href="mailto:shiva_khanal@hotmail.com">shiva_khanal@hotmail.com</a>>) escribió:<o:p></o:p></p>
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<p class="MsoNormal"><span style="color:black">Hi,</span><span style="font-size:12.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I am interested to run the spatial-mode PCA on raster time series. In R it is implemented as an ‘EOF’ function in spacetime Package. The function transposes the raster stack and applies ‘prcomp’ function. I would like to know if there
is any possible way to implement i.pca similar to this approach.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Interestingly, I found a very good tutorial on GRASS raster time series at
<a href="https://grasswiki.osgeo.org/wiki/Temporal_data_processing/GRASS_R_raster_time_series_processing" target="_blank">
https://grasswiki.osgeo.org/wiki/Temporal_data_processing/GRASS_R_raster_time_series_processing</a> This includes the example using spacetime package to read GRASS raster time series into R.<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">there's also an alternative way to export raster time series from GRASS that was not there at the moment of creating the wiki: the add-on
<a href="http://t.rast.out.xyz">t.rast.out.xyz</a> [0] that produces a table with xy coordinates and all dates in columns. You can then import that into R, transpose and run prcomp, EOF or others. Do you want it for gap-filling?<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">If you dare to implement EOF in GRASS, please go ahead!! I will be very happy to test and provide feedback, I've been wishing for such a thing (and also DINEOF) for a while :)
<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Maybe the devs can provide hints and advice on how to address it.
<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Best, <o:p></o:p></p>
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<p class="MsoNormal">Vero<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">[0] <a href="https://grass.osgeo.org/grass74/manuals/addons/t.rast.out.xyz.html">
https://grass.osgeo.org/grass74/manuals/addons/t.rast.out.xyz.html</a><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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