2d plotting and colours

Wed, Mar 30, 2005 5:17 PM

Thank you very much.

the code
plot(x, col = s)
points(cl$centers, col = s, pch = 8, cex=2)

does not plot the points according to the group colors. The plots are used 
to identify the groups by colors

That could be done by

plot(x, col = cl$cluster)

This means that we need to set the default colours , say col = cl$cluster = 
a set of group numbers say 1...10 should produce 10 distinct colours points 
grouped by colour.

how to do this when you have more than 8 group colours to plot

From: "Mulholland, Tom" <Tom.Mulholland at dpi.wa.gov.au>
To: <r-help at stat.math.ethz.ch>,"Asha Jayanthi" <ashajayanthi at hotmail.com>
Subject: RE: [R] 2d plotting and colours
Date: Wed, 30 Mar 2005 15:59:46 +0800

And getting back to your question about the palette

there are a lot of ways to do this

assuming you have just started a session

palette()
# will give
#[1] "black"   "red"     "green3"  "blue"    "cyan"
#[6] "magenta" "yellow"  "gray"

palette(rainbow(24))  # There's also 'heat.colors' & 'topo.colors'
palette()

# [1] "red"         "#FF4000"     "#FF8000"
# [4] "#FFBF00"     "yellow"      "#BFFF00"
# [7] "#80FF00"     "#40FF00"     "green"
#[10] "#00FF40"     "#00FF80"     "#00FFBF"
#[13] "cyan"        "deepskyblue" "#0080FF"
#[16] "#0040FF"     "blue"        "#4000FF"
#[19] "#8000FF"     "#BF00FF"     "magenta"
#[22] "#FF00BF"     "#FF0080"     "#FF0040"

palette(rgb((0:15)/15, g=0,b=0, names=paste("red",0:15,sep=".")))
palette()
# [1] "black"   "#110000" "#220000" "#330000" "#440000"
# [6] "#550000" "#660000" "#770000" "#880000" "#990000"
#[11] "#AA0000" "#BB0000" "#CC0000" "#DD0000" "red2"
#[16] "red"

If you are looking to use colours that take account of colour blindness
you could try the package dichromat. (I think 2.1 will have some of this 
inbuilt)

Once you look through the help files associated with some of these options 
you
will find the way that best suits your method of working.

Tom

-----Original Message-----
From: Uwe Ligges [mailto:ligges at statistik.uni-dortmund.de]
Sent: Wednesday, 30 March 2005 3:18 PM
To: TEMPL Matthias
Cc: r-help at stat.math.ethz.ch; Asha Jayanthi
Subject: Re: [R] 2d plotting and colours


TEMPL Matthias wrote:

Hi!

There are more than 8 colors.

Yes, e.g. for rgb space there are 16777216, see ?rgb.

Uwe Ligges

x <- rbind(matrix(rnorm(100, sd = 0.3), ncol = 2),
                matrix(rnorm(100, mean = 1, sd = 0.3), ncol = 2))

(cl <- kmeans(x, i, 20))

s <- c("tomato4", "turquoise", "slateblue", "wheat",

"snow", "skyblue",

"peru", "pink")
# see at:
colors()

plot(x, col = s)

points(cl$centers, col = s, pch = 8, cex=2)


Best,
Matthias

Hi!

I am new to R just 3 days in it and i apologize if my
questions seem very
trivial and consumed your valuable time.

I am coding in perl and i stumbled upon R regarding plotting good
statistical graphs.

I tried the kmean clustering for a large matrix ,say > 150 *
150 . I tried
the example code given in the tutorial to perform 2d plot

# i ranges from 2 to 10
cl <- kmeans(x, i, 20)
plot(x, col = cl$cluster)
points(cl$centers, col = 1:i )

I see that there are only 8 colours defined , namely
black,red,green,blue,cyan,magenta,yello,gray.

How should i set my colour preferences to obtain my palette
of colours? I
checked in the totorial which talks about R.colors and
palatte , but i
failed to understand how to set it.

Thank You

Asha

2d plotting and colours

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