Is there any effective way to get distinct geometric plotting symbols and colors for plots involving more than 25 groups? Thanks. Dr. Marc R. Feldesman Professor and Chairman Emeritus Anthropology Department - Portland State University email: feldesmanm at pdx.edu email: feldesman at attglobal.net fax: 503-725-3905 "Don't knock on my door if you don't know my Rottweiler's name" Warren Zevon "Its midnight and I'm not famous yet" Jimmy Buffett
The answer is yes. Have a look to "pch" and "col" plot parameters on R-help. A.S. ---------------------------- Alessandro Semeria Models and Simulations Laboratory Montecatini Environmental Research Center (Edison Group), Via Ciro Menotti 48, 48023 Marina di Ravenna (RA), Italy Tel. +39 544 536811 Fax. +39 544 538663 E-mail: alessandro.semeria at cramont.it
Dear Marc,
I may misunderstand your question, so perhaps this answer isn't what
you're
looking for:
A short time ago, Henrik Bengtsson posted a function to r-help (search for
plotSymbols in the list archive) that displays all available symbols. I
think that it's fair to say that fewer than 25 of these could be
characterized as distinct geometric symbols.
On the other hand, the colour space for R is very large; see, e.g.,
help("colours") and the help pages linked to it.
Moreover, if you take combinations of filled symbols and even basic colours,
you could in principle represent more than 25 groups. I wonder, however,
whether someone viewing a graph with so many different symbols will be able
to parse the information.
I hope this helps,
John
> -----Original Message-----
> From: r-help-bounces at stat.math.ethz.ch
> [mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Marc
> R. Feldesman
> Sent: Thursday, April 01, 2004 11:40 PM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Plot symbols for more than 25 groups
>
> Is there any effective way to get distinct geometric plotting
> symbols and colors for plots involving more than 25 groups?
>
> Thanks.
>
>
>
>
> Dr. Marc R. Feldesman
> Professor and Chairman Emeritus
> Anthropology Department - Portland State University
> email: feldesmanm at pdx.edu
> email: feldesman at attglobal.net
> fax: 503-725-3905
>
>
> "Don't knock on my door if you don't know my Rottweiler's
> name" Warren Zevon "Its midnight and I'm not famous
yet"
> Jimmy Buffett
>
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At 05:16 AM 4/2/2004, Carlisle Thacker watched in amazement as electrons turned into magical things called words: >Marc, > >It is very difficult for the eye to distinguish even 25 symbols or 25 >colors on the same plot. I find that my brain tends to saturate at 5 of >each, and using 5 symbols each taking five colors to get 25 groups is >hard to comprehend unless there colors and symbols correspond to quite >different characteristics of the data. Maybe there is a better way to >display your data. > This is a straight plot of the bivariate means of 38 different groups of primates. We've already stripped out the data scatter around each mean, but we want to highlight where each group lies in the 2-dimensional space. We haven't found a more effective way to illustrate this in a single plot than using a simple bivariate scatter.
Marc R. Feldesman <feldesmanm <at> pdx.edu> writes:> Is there any effective way to get distinct geometric plotting symbols and > colors for plots involving more than 25 groups?Not sure if geometric shapes is essential but if not you could plot them with different letters (or LETTERS). The following plots one point for each state of 26 states using a, b, ...,z : data(state) df <- data.frame(state.x77)[1:26,] plot(Life.Exp ~ Income, data=df, pch=letters) # Alternately you could plot them all with points but label each point # with a different letter: plot(Life.Exp ~ Income, data=df, pch=20) text( df$Income, df$Life.Exp, LETTERS, pos=3) # or even use the state abbreviations in this case: plot(Life.Exp ~ Income, data=df, pch=20) text(df$Income,df$Life.Exp,state.abb[1:26],pos=3)
A rainbow has a continuous distribution of wavelengths. These are not at all the same thing as colors! Quoting Prof Brian Ripley <ripley at stats.ox.ac.uk>:> > You would do well to get people to recognize more than a dozen spot > colours, too -- we are tuned to recognizing quite large blobs of colour. > We see only about a dozen colours in a rainbow, which has infinitely many > and they are adjacent. > > -- > Brian D. Ripley, ripley at stats.ox.ac.uk > Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ > University of Oxford, Tel: +44 1865 272861 (self) > 1 South Parks Road, +44 1865 272866 (PA) > Oxford OX1 3TG, UK Fax: +44 1865 272595 > > ______________________________________________ > R-help at stat.math.ethz.ch mailing list > https://www.stat.math.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide! > http://www.R-project.org/posting-guide.html >____________________ Ken Knoblauch Inserm U 371 Cerveau et Vision 18 avenue du Doyen Lepine 69675 Bron cedex France tel: +33 (0)4 72 91 34 77 fax: +33 (0)4 72 92 34 61 portable: 06 84 10 64 10