By default the z-values are split into equal ranges to match the number of colors. The first color is then for first interval from min(z) etc. Look at the code for image.default for clarity - there seems to be some influence from the "oldstyle" parameter. If you want to be 100% sure about which colors match which range, consider specifying the ranges in "breaks".
Schalk Heunis On Sun, Sep 6, 2009 at 4:50 PM, FMH<kagba2...@yahoo.com> wrote: > Hi, > > Thank you for your response. I'm looking for the names of the colors denoted > by these codes and what do these colors represent for. > For instance, if we use topo.colors(5) in the image function, five different > colors will be used in which its codes are denoted as: > > [1] "#4C00FFFF" "#004CFFFF" "#00E5FFFF" "#00FF4DFF" "#FFFF00FF" > > So, my first question is what type of color do these codes represent for? Are > they white, red,...? > > My second question is, if we use this topo.colors(5) in image function to > denote the temperature values for intance, what are these colors represent > for? Does the first color, "#4C00FFFF" represent the lower/medium/higher > temperature? > > I do hope you could advice me on this matter? > > Thank you > Fir > > > > > ----- Original Message ---- > From: FMH <kagba2...@yahoo.com> > To: Steve Lianoglou <mailinglist.honey...@gmail.com> > Sent: Sunday, September 6, 2009 3:41:02 PM > Subject: Re: [R] Color index in image function > > Hi, > > Thank you for your response. I'm looking for the name of the colors denoted > by this code and what are these colors representing for. > > For instance, if we use topo.colors(5) in the image function, five different > colors will be used in which its codes are denoted as: > > [1] "#4C00FFFF" "#004CFFFF" "#00E5FFFF" "#00FF4DFF" "#FFFF00FF" > > So, my first question is what type of color does these codes represent > for? Are they white, red,...? > > My second question is, if we use this topo.colors(5) in image function to > denote the temperature values for intance, what are these colors represent > for? Does the first color, "#4C00FFFF" represent the lower/medium/higher > temperature? > > I do hope you could advice me on this matter? > > Thank you > Fir > > > > > > > > ----- Original Message ---- > From: Steve Lianoglou <mailinglist.honey...@gmail.com> > To: FMH <kagba2...@yahoo.com> > Cc: r-help@r-project.org > Sent: Sunday, September 6, 2009 3:20:25 PM > Subject: Re: [R] Color index in image function > > Hi, > > On Sat, Sep 5, 2009 at 7:06 AM, FMH<kagba2...@yahoo.com> wrote: >> Dear All, >> >> I was looking for the color index in image function, such as from >> topo.colors(n) and etc. but still never found it. For instance, from the >> help menu. > > The answer is in the code: > >> ########################################### >> # Volcano data visualized as matrix. Need to transpose and flip >> # matrix horizontally. >> image(t(volcano)[ncol(volcano):1,]) >> >> # A prettier display of the volcano >> x <- 10*(1:nrow(volcano)) >> y <- 10*(1:ncol(volcano)) >> image(x, y, volcano, col = terrain.colors(100), axes = FALSE) > > Right here: > > R> terrrain.colors(100) > > [1] "#00A600FF" "#03A700FF" "#07A800FF" "#0AAA00FF" "#0EAB00FF" ... > > Is that what you mean? > -steve > > -- > Steve Lianoglou > Graduate Student: Computational Systems Biology > | Memorial Sloan-Kettering Cancer Center > | Weill Medical College of Cornell University > Contact Info: http://cbio.mskcc.org/~lianos/contact > > > > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
