[GRASS-dev] reg i.pca module

[Nikos Alexandris]

On Wednesday 06 of February 2013 23:19:36 Rashad M wrote:

> Hi All,

Hi Rashad!

> i.pca outputs raster bands and the pixel values are transformed obivously.
> But anyone can tell me how the transformation works
> 
> if a pixel P1 has value X after i.pca it will be Y
> 
> Is there any specific math equation that is applied to every pixel by PCA?

For sure. There are two _good_ grassy-sources to start with:

1. the i.pca's manual
http://grass.osgeo.org/grass70/manuals/i.pca.html

2.the GRASS-Wiki page explains all one needs to know -- even if it requires 
some clean-up
<http://grasswiki.osgeo.org/wiki/Principal_Components_Analysis>

And, of course (sorry for insisting and self-advertising) my work (available 
at the link I've PMed to you).  I've put a lot of effort to compile material & 
explain what PCA is, what it does and how it does it.  It would be really 
nice, for me, to have some feedback if it helps, in any way, to understand 
PCA.

If you had a look and found the material useless, please, be so kind and tell 
me so -- strait (PM or ML, the same).  I'd really like to know what you think 
as I am planing to continue this effort in time, and expand it.

Best, Nikos
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 230 bytes
Desc: This is a digitally signed message part.
URL: <http://lists.osgeo.org/pipermail/grass-dev/attachments/20130207/3bc300e2/attachment.pgp>