spatstat::affine.im

Enviat el: divendres, 10 / agost / 2012 20:43
Per a: JOSE MANUEL BLANCO MORENO; r-sig-geo at r-project.org
Tema: Re: [R-sig-Geo] spatstat::affine.im

Hi Jose Manuel,

I don't think it is exactly a bug. Just try indicating the dimensions of
the resulting image:


> vec <- rnorm(1200)
> mat <- matrix(vec, nrow=30, ncol=40)
> whitenoise <- im(mat)
> whitenoise2 <- affine(whitenoise, mat=diag(c(2,3)),dimyx=c(30,40))
> whitenoise2
real-valued pixel image
30 x 40 pixel array (ny, nx)
enclosing rectangle: [1, 81] x [1.5, 91.5] units

Cheers,

Marcelino



Con fecha 10/8/2012, "JOSE MANUEL BLANCO MORENO" <jmblanco at ub.edu>
escribi?:

>Regarding my previous query, the problem is in fact in line 22-23 of function affine.im, when calling affinexy; when calling affine.im for a rectangular image but applying a non-diagonal matrix, there is no problem, because affinexy is not executed.
>
>
>
>This example does not work (as  before):
>
>
>
>vec <- rnorm(1200)
>mat <- matrix(vec, nrow=30, ncol=40)
>whitenoise <- im(mat)
>whitenoise2 <- affine(whitenoise, mat=diag(c(2,3)))
>
>
>
>But this one does:
>
>
>
>vec <- rnorm(1200)
>mat <- matrix(vec, nrow=30, ncol=40)
>whitenoise <- im(mat)
>whitenoise2 <- affine(whitenoise, mat=matrix(c(1,8,8,1), ncol=2))
>
>
>
>Looks like a bug?
>
>---------------------------------------
>Jos? M. Blanco-Moreno
>Dept. de Biologia Vegetal (Bot?nica)
>Facultat de Biologia
>Universitat de Barcelona
>Av. Diagonal 643
>08028 Barcelona
>SPAIN
>---------------------------------------
>phone: (+34) 934 039 863
>fax: (+34) 934 112 842
>---------------------------------------
>
>________________________________
>De: JOSE MANUEL BLANCO MORENO
>Enviat el: divendres, 10 / agost / 2012 15:13
>Per a: r-sig-geo at r-project.org
>Tema: spatstat::affine.im
>
>
>Dear users & experts,
>
>
>
>Does anyone know if affine transformation of images (function affine.im in spatstat) should work for non-square images? I thought it should, but I have tried:
>
>
>
>vec <- rnorm(1200)
>mat <- matrix(vec, nrow=30, ncol=40)
>whitenoise <- im(mat)
>whitenoise2 <- affine(whitenoise, mat=diag(c(2,3)))
>
>
>
>But I get:
>
>
>
>Error in im(v, xcol = xcol, yrow = yrow, xrange = newbox$xrange, yrange = newbox$yrange,  :
>  Length of yrow does not match nrow(mat)
>In addition: Warning message:
>In rbind(X$x, X$y) :
>  number of columns of result is not a multiple of vector length (arg 2)
>
>
>
>However if I modify the example allowing for a square image it works perfectly:
>
>
>
>vec <- rnorm(900)
>mat <- matrix(vec, nrow=30, ncol=30)
>whitenoise <- im(mat)
>whitenoise2 <- affine(whitenoise, mat=diag(c(2,3)))
>
>And the only difference that I can spot between these matrices/images is the shape of the image itself.
>
>
>
>Affine should work for non-square images, isn't it? Or I am wrong? Is there any way to circumvent this problem?
>
>
>
>These are version details:
>
>R version 2.15.1 (2012-06-22)
>Platform: i386-pc-mingw32/i386 (32-bit)
>
>locale:
>[1] LC_COLLATE=English_United States.1252  LC_CTYPE=English_United States.1252    LC_MONETARY=English_United States.1252
>[4] LC_NUMERIC=C                           LC_TIME=English_United States1252
>
>attached base packages:
>[1] stats     graphics  grDevices utils     datasets  methods   base
>
>other attached packages:
>[1] spatstat_1.28-1 deldir_0.0-19   mgcv_1.7-18
>
>loaded via a namespace (and not attached):
>[1] grid_2.15.1    lattice_0.20-6 Matrix_1.0-6   nlme_3.1-104   tools_2.15.1
>
>
>
>---------------------------------------
>Jos? M. Blanco-Moreno
>Dept. de Biologia Vegetal (Bot?nica)
>Facultat de Biologia
>Universitat de Barcelona
>Av. Diagonal 643
>08028 Barcelona
>SPAIN
>---------------------------------------
>phone: (+34) 934 039 863
>fax: (+34) 934 112 842
>---------------------------------------
>
>
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