[R-sig-Geo] Problem with "image" function

Cristina Silva csilva at ipimar.pt
Fri Jul 22 19:58:57 CEST 2011

Dear list members,

I have a SpatialGridDataFrame with sea depths. I have previously plotted 
this object using "image" with a grey scale. I have used exactly the 
same script and now the result is crossed by horizontal white lines.

As the script used was based in chunk no. 91 of cm_mod.R (book ASDAR, 
figure 2.7), I repeated this script

> oopar <- par(mar=c(1,1,1,1)+0.1)
> grys <- grey.colors(8, 0.55, 0.95, 2.2)
> image(auck_el1, "band1", col=grys)
> plot(auck_gshhs, add=TRUE, pbg="white")
> transect_sp <- SpatialPoints(coords=cbind(seq(174.458,175.3,0.000833333),
>   c(-37.03625)), proj4string=CRS("+proj=longlat +ellps=WGS84"))
> plot(transect_sp, add=TRUE, pch="-", cex=2)
> legend_image(c(174.2,174.25), c(-37.5,-37.2), auck_el1$band1, 
> vertical=TRUE,
>  offset.leg=0.8, col=grys)
> par(oopar)

and the result was also crossed by the same white horizontal lines.

I am using R version 2.13.1. I didn't have any problems with previous 

Thanks for your attention


Cristina Silva
Unidade de Recursos Marinhos e Sustentabilidade
Av. de Brasília, 1449-006 Lisboa
Tel.: 351 21 3027096
Fax: 351 21 3015948
csilva at ipimar.pt

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