Yes, look for argument alpha e.g. in ?rgb or ?bpy.colors On 03/06/2012 04:49 PM, Mauricio Zambrano-Bigiarini wrote: > On 05/03/12 14:40, Edzer Pebesma wrote: >> This has now been changed/repared in sp on r-forge (svn), and will >> appear from sp 0.9-97 on. A test run would be: >> >> library(sp) >> xyz = data.frame(expand.grid(x=1:10,y=1:10),rnorm(100)) >> coordinates(xyz)=~x+y >> spplot(xyz, cex=10) >> >> which used to plot points in value order, and does now in data record >> order. >> >> I put up resulting graphs, for comparison, at >> http://ifgi.uni-muenster.de/~epebe_01/xyz.html >> >> As this change may make some of your spplot's for points different, if >> there are objections against this change (which I consider an >> improvement, if not a bug fix), it is time now to let me / us know. > > Would it be possible to set a degree of transparency for the > overlapping points in spplot ? > > Thanks in advance, > > Mauricio Zambrano-Bigiarini > - > ======================================================= > FLOODS Action > Water Resources Unit (H01) > Institute for Environment and Sustainability (IES) > European Commission, Joint Research Centre (JRC) > webinfo : http://floods.jrc.ec.europa.eu/ > ======================================================= > DISCLAIMER: > "The views expressed are purely those of the writer > and may not in any circumstances be regarded as stating > an official position of the European Commission." > ======================================================= > Linux user #454569 -- Ubuntu user #17469 > ======================================================= > "If Columbus had turned back, no one would have blamed him. > Of course, no one would have remembered him either." > (Source Unknown) > > >> >> On 03/02/2012 09:03 PM, MacQueen, Don wrote: >>> I have a SpatialPointsDataFrame object in which many points are very >>> close >>> together, such that the markers (plotting characters) tend to >>> overlap. (Of >>> course, this depends on marker size and the scale at which I plot; if I >>> "zoom in" there is less overlap.) >>> >>> It appears that when markers overlap, spplot() places a marker >>> associated >>> with the larger value after, and therefore on top of, a marker >>> associated >>> with a smaller value. >>> >>> Am I correct? Or more generally, what is the algorithm that >>> determines the >>> order in which markers are added? >>> >>> >>> I have searched ?spplot and related help pages and haven't found an >>> explanation (at least, not yet). >>> >>> I can add that I don't believe markers are placed in the order in which >>> they appear in the SpatialPointsDataFrame. I say this because when I >>> attempt to reproduce an spplot using base graphics plot() I have to sort >>> from smallest to largest value to succeed. >>> >>> I can probably provide a small reproducible example if necessary, but >>> I'm >>> hoping it's not necessary. >>> >>> Here are my actual commands. >>> >>> tmps is the SpatialPointsDataFrame. >>> tmp is coordinates(tmps) >>> (they have the same number of rows in the same order) >>> >>> Note that I'm using the cuts argument to break a continuous variable >>> ('cpm2') into bins. I have carefully matched the colors in tmps$col2 >>> with >>> the cbin.cols object passed to spplot(), and the break points for the >>> bin >>> boundaries, so I believe that everything else that could affect the >>> final >>> appearance, other than the order in which the markers are placed, is >>> controlled. >>> >>> #1 using spplot >>> spplot(tmps,c('cpm2'), >>> key.space='right', >>> legendEntries=cbin.lbls, >>> cuts=cbin.brks, >>> col.regions=cbin.cols, >>> cex=0.4) >>> >>> #2 using base graphics >>> plot(tmp[,1],tmp[,2], asp=1, cex=0.6, pch=16, col=tmps$col2) >>> >>> >>> >>> Thanks >>> -Don >>> >> > > > -
-- Edzer Pebesma Institute for Geoinformatics (ifgi), University of Münster Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251 8333081, Fax: +49 251 8339763 http://ifgi.uni-muenster.de http://www.52north.org/geostatistics e.pebe...@wwu.de _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo