R help - Aug 2005 - use different symbols for frequency in a plot

suppose I have the following data

x<-c(rep(.1,5),rep(.2,6),rep(.4,10),rep(.5,20))
y<-c(rep(.5,3),rep(.6,8),rep(1.2,8),rep(2.5,18),rep(3,4))

If I plot(x,y) in R, I will only get seven distinct
points. What I want to do is to use different symbols
to show the frequency at each point.

e.g. if the frequncey is between 1 and 5, then I plot
the point as a circle; if the frequency is between 6
and 10, then I plot the point as a square; if the
frequency is above 10, then I plot the point as a
triangle.

I am not sure how to do this in R. Can anybody help me?

You might consider one of these approaches instead:

plot(jitter(x), jitter(y))

or

pdf(file="c:/AlphaExample.pdf", version = "1.4")

plot(x, y, col = rgb(1, 0, 0, .2), pch = 16)

dev.off()

Kerry Bush wrote:
> suppose I have the following data
> 
> x<-c(rep(.1,5),rep(.2,6),rep(.4,10),rep(.5,20))
> y<-c(rep(.5,3),rep(.6,8),rep(1.2,8),rep(2.5,18),rep(3,4))
> 
> If I plot(x,y) in R, I will only get seven distinct
> points. What I want to do is to use different symbols
> to show the frequency at each point.
> 
> e.g. if the frequncey is between 1 and 5, then I plot
> the point as a circle; if the frequency is between 6
> and 10, then I plot the point as a square; if the
> frequency is above 10, then I plot the point as a
> triangle.
> 
> I am not sure how to do this in R. Can anybody help me?
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
> 
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Group by which variable ? If you mean the joint distribution of 'x' and
'y' then something along the following lines

 x <- rep( c(0.1, 0.2, 0.4, 0.5),      c(5, 6, 10, 20) )
 y <- rep( c(0.5, 0.6, 1.2, 2.5, 3.0), c(3, 8, 8, 18, 4) )

 new     <- factor( paste(x, y, sep="_") )
 tb      <- table(new)

 pchcode <- cut(tb , c(-Inf, 1, 5, 6, 10, Inf), labels=F)

 tmp     <- t( sapply( strsplit( names(tb), split="_") , c ) )
 df      <- data.frame( x=tmp[ ,1], y=tmp[ ,2], 
                        freq=as.vector(tb), pchcode = pchcode -1 )

     x   y freq pchcode
 1 0.1 0.5    3       1
 2 0.1 0.6    2       1
 3 0.2 0.6    6       2
 4 0.4 1.2    8       3
 5 0.4 2.5    2       1
 6 0.5 2.5   16       4
 7 0.5   3    4       1

And now to plot it, we use points() repeatedly.

 plot( as.numeric(df$x), as.numeric(df$y), type="n" )

 for( i in unique( df$pchcode ) ){
    w <- which( df$pchcode == i )
    points( df$x[w], df$y[w], pch=as.numeric(i) )
 }

I am sure someone else will come up with a neater solution.


Can I also suggest that you try the following

  plot( jitter(x), jitter(y) )

or better still the following

  library(hexbin)
  plot( hexbin(x, y) )


Regards, Adai

On Mon, 2005-08-08 at 11:57 -0700, Kerry Bush wrote:
> suppose I have the following data
> 
> x<-c(rep(.1,5),rep(.2,6),rep(.4,10),rep(.5,20))
> y<-c(rep(.5,3),rep(.6,8),rep(1.2,8),rep(2.5,18),rep(3,4))
> 
> If I plot(x,y) in R, I will only get seven distinct
> points. What I want to do is to use different symbols
> to show the frequency at each point.
> 
> e.g. if the frequncey is between 1 and 5, then I plot
> the point as a circle; if the frequency is between 6
> and 10, then I plot the point as a square; if the
> frequency is above 10, then I plot the point as a
> triangle.
> 
> I am not sure how to do this in R. Can anybody help me?
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
http://www.R-project.org/posting-guide.html
>

On Mon, 2005-08-08 at 11:57 -0700, Kerry Bush wrote:
> suppose I have the following data
> 
> x<-c(rep(.1,5),rep(.2,6),rep(.4,10),rep(.5,20))
> y<-c(rep(.5,3),rep(.6,8),rep(1.2,8),rep(2.5,18),rep(3,4))
> 
> If I plot(x,y) in R, I will only get seven distinct
> points. What I want to do is to use different symbols
> to show the frequency at each point.
> 
> e.g. if the frequncey is between 1 and 5, then I plot
> the point as a circle; if the frequency is between 6
> and 10, then I plot the point as a square; if the
> frequency is above 10, then I plot the point as a
> triangle.
> 
> I am not sure how to do this in R. Can anybody help me?
You might want to review this recent post by Deepayan Sarkar:

https://stat.ethz.ch/pipermail/r-help/2005-July/074042.html

with modest modification you can replace his example, which plots the
frequencies with:

x <- c(rep(.1,5),rep(.2,6),rep(.4,10),rep(.5,20))
y <- c(rep(.5,3),rep(.6,8),rep(1.2,8),rep(2.5,18),rep(3,4))

temp <- data.frame(x, y)

foo <- subset(as.data.frame(table(temp)), Freq > 0)
> foo
     x   y Freq
1  0.1 0.5    3
5  0.1 0.6    2
6  0.2 0.6    6
11 0.4 1.2    8
15 0.4 2.5    2
16 0.5 2.5   16
20 0.5   3    4

# Use cut() to create the bins and specify the plotting symbols
# for each bin, which are the 'label' values
foo$sym <- with(foo, cut(Freq, c(0, 5, 10, Inf), 
                         labels = c(21, 22, 24))) 


# convert 'foo' to all numeric from factors above for plotting
foo <- apply(foo, 2, function(x) as.numeric(as.character(x)))

> foo
     x   y Freq sym
1  0.1 0.5    3  21
5  0.1 0.6    2  21
6  0.2 0.6    6  22
11 0.4 1.2    8  22
15 0.4 2.5    2  21
16 0.5 2.5   16  24
20 0.5   3    4  21


# Now do the plot. Keep in mind that 'foo' is now
# a matrix, rather than a data frame
plot(foo[, "x"], foo[, "y"], pch = foo[, "sym"])


HTH,

Marc Schwartz