CODEWITHSUNDEEP
rdata-visualization
Sanjuro
Sanjuro

Reputation: 87

Scatter plot with color of data points specified with the data

I'm trying to create a pretty simple scatter plot with two data series. I would like to specify the color of each point through a fourth column in the dataframe I'm using. I've got the scatter plot itself close to where I want it, with two different glyphs for the two series, but the colors are not being assigned to the right points. I'm pretty new to R so I'm not sure where to go from here. Any help would be appreciated. Sample data and code attached (can't upload images yet).

Sample Data:

x   y   group   color
0   0   g   red
2   -1  g   blueviolet
0   -1  g   brown
2   -2  g   blueviolet
0   -11 g   blue
2   -6  g   blue
0   1   g   coral
0   -2  g   blue
2   -1  h   blueviolet
0   -1  h   brown
2   -2  h   blueviolet
0   -11 h   blue
2   -6  h   blue
0   1   h   coral
2   -8  h   blue
4   -2  h   coral
1   -5  h   brown
1   -9  h   violet
-2  2   h   blue

Sample R code:

ztest=read.table(file="ztest.txt",sep="\t",header=TRUE)
plot(ztest$x,ztest$y,type='n')
points(ztest[ztest$group=="g",]$x,ztest[ztest$group=="g",]$y,col=ztest$color,pch=3,cex=.75)
points(ztest[ztest$group=="h",]$x,ztest[ztest$group=="h",]$y,col=ztest$color,pch=1,cex=1.75)

Upvotes: 2

Views: 4462

Answers (2)

R-noob
R-noob

Reputation: 26

You seem to be subsetting the points, but not subsetting the colours. Instead of 

points(ztest[ztest$group=="g",]$x,ztest[ztest$group=="g",]$y,col=ztest$color, ...

try

points(ztest[ztest$group=="g",]$x,ztest[ztest$group=="g",]$y,col=as.character(ztest[ztest$group=="g",]$color), ....

Hope this helps

Upvotes: 1

Peter Ellis
Peter Ellis

Reputation: 5894

The answer is probably that color is being interpreted as a factor when you read it in with read.table. Try

ztest$color <- as.character(ztest$color)

and see if it works.

Or ggplot2 is awesome for this sort of thing. AFter you've done the above, try as an alternative to your approach

library(ggplot2)
qplot(x,y, color=color, shape=group, data=ztest, size=group) + 
    scale_color_identity(legend=FALSE) +
    scale_shape_manual(values=c(3,1)) +
    scale_size_manual(values=c(3,6))

Upvotes: 2

Related Questions