2d plotting and colours

-----Original Message-----
From: Asha Jayanthi [mailto:ashajayanthi at hotmail.com]
Sent: Thursday, 31 March 2005 2:36 PM
To: Mulholland, Tom; r-help at stat.math.ethz.ch
Subject: RE: [R] 2d plotting and colours


Thank you.

mycols <- c("brown","orange","tomato")
plot(x,col = mycols[cl$cluster])

this works. I can define distinct colours and check the graph.

the rest of the examples does not give a wide palette to choose from

Asha

From: "Mulholland, Tom" <Tom.Mulholland at dpi.wa.gov.au>
To: "Asha Jayanthi" 

<ashajayanthi at hotmail.com>,<r-help at stat.math.ethz.ch>

Subject: RE: [R] 2d plotting and colours
Date: Thu, 31 Mar 2005 10:14:13 +0800

Since I was only concentrating on colour issues and not on 

your specific 

problem I was just showing the possibilities.

Does this code help

n <- 5
par(mfrow = c(2,2))
palette("default")
barplot(1:25,col = 1:25)
palette(rainbow(n))
barplot(1:25,col = 1:25)
palette(rgb((0:15)/15, g=0,b=0, names=paste("red",0:15,sep=".")))
barplot(1:25,col = 1:25)


require(cluster)
x <- runif(100) * 8 + 2
cl <- kmeans(x, n)
palette(rainbow(n))
plot(x, col = cl$cluster)
abline(h = cl$centers, lty = 2,col = "grey" )
palette(palette()[order(cl$centers)])
points(x,col = cl$cluster,pch = 20,cex = 0.4)

However you may wish to choose your colours in a way that is 

different from 

cl$cluster which is why I changed the palette before 

plotting the points. 

You should see that they now are ordered from bottom to top 

of the last 

plot.

You could also choose to create a vector with your colours 

and then use the 

value in cl$cluster to select the colours

mycols <- rainbow(n)
plot(x,col = mycols[cl$cluster])

Tom

-----Original Message-----
From: Asha Jayanthi [mailto:ashajayanthi at hotmail.com]
Sent: Thursday, 31 March 2005 9:17 AM
To: r-help at stat.math.ethz.ch
Subject: RE: [R] 2d plotting and colours


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