<html><body><div style="color:#000; background-color:#fff; font-family:verdana, helvetica, sans-serif;font-size:10pt"><div>Hello all,</div><div><br></div><div>I am *very* new to R and am experimenting with the GRASS / R interface to look at correlation of elevation and spectral values.</div><div><br></div><div>Reading through the literature and mailing list, I have imported my GRASS rasters to R as a dataset looked at the summary statistics and then attempted to run a correlation analysis using cor, along the lines of the example here:<br></div><div><br></div><div><span>map <- readRAST6(c("lageado_10k_fisher_K_15x15",
</span><br><span> "lageado_10k_fisher_K_25x25"))
</span><br><span>summary(map)
</span><br><span>cor(as(map, "data.frame")) <br></span></div><div><br><span></span></div><div><span>and get the output:<br></span></div><div><br></div><div> coombe_rev_LRM intensity_coombe x y<br>coombe_rev_LRM 1 NA NA NA<br>intensity_coombe NA 1.00000000 -0.1525509
0.09057913<br>x <span class="tab"> </span>NA -0.15255095 1.0000000 0.00000000<br>y <span class="tab"> </span>NA 0.09057913 0.0000000 1.00000000<br><br></div><div><br></div><div>so the correlation is running on the x and y values of the rasters not the z?</div><div><br></div><div>How do I begin to assess correlation in the z value of two rasters?</div><div><br></div><div>Many thanks for reading, (and sorry if my question seems stupid or I have missed something
obvious)</div><div><br></div><div>Rebecca<br></div><div><br></div><div><br></div></div></body></html>