R help - Apr 2012 - Legend based on levels of a variable

I have a bivariate plot of axis2 against axis1 (data below). I would like
to use different size, type and color for points in the plot for the point
coming from different region. For some reasons, I cannot get it done. Below
is my code.

col <- rep(c("blue", "red", "darkgreen"), c(16,
16, 16))
## Choose different size of points
cex <- rep(c(1, 1.2, 1), c(16, 16, 16))
## Choose the form of the points (square, circle, triangle and
diamond-shaped
pch <- rep(c(15, 16, 17), c(16, 16, 16))

plot(axis1, axis2, main="My plot", xlab="Axis 1",
ylab="Axis 2",
 col=c(Category, col), pch=pch, cex=cex)
legend(4, 12.5, c("NorthAmerica", "SouthAmerica",
"Asia"), col = col,
       pch = pch, pt.cex = cex, title = "Region")

I also prefer a control on what kind of point I want to use for different
levels of Region. Something like this:
legend(4,12.5, col(levels(Category), Asia="red",
NorthAmerica="blue",
SouthAmerica="green"))

Thanks,
Kumar

  Region axis1 axis2  NorthAmerica 5 14  NorthAmerica 8 13  NorthAmerica 8
11  NorthAmerica 6 11  NorthAmerica 5 13  SouthAmerica 8 17  SouthAmerica 7
16  SouthAmerica 7 13  SouthAmerica 8 14  SouthAmerica 6 17  Asia 7 13  Asia
6 15  Asia 7 14  Asia 5 13  Asia 4 16

	[[alternative HTML version deleted]]

I think there may 3 legends should be added in your plot
the argument col, pch and pt.cex should be in the same length with legend,
but the objects col, pch
 and cex you defined former have 16*3 length. I guess the follow codes may
work

col <- rep(c("blue", "red", "darkgreen"), c(16,
16, 16))
## Choose different size of points 
cex <- rep(c(1, 1.2, 1), c(16, 16, 16)) 
## Choose the form of the points (square, circle, triangle and 
diamond-shaped 
pch <- rep(c(15, 16, 17), c(16, 16, 16)) 

plot(axis1, axis2, main="My plot", xlab="Axis 1",
ylab="Axis 2",
 col=c(Category, col), pch=pch, cex=cex) 
legend(4, 12.5, c("NorthAmerica", "SouthAmerica",
"Asia"), col unique(col),
       pch = unique(pch), pt.cex = unique(cex), title = "Region") 

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Hi
> 
> I have a bivariate plot of axis2 against axis1 (data below). I would 
like
> to use different size, type and color for points in the plot for the 
point
> coming from different region. For some reasons, I cannot get it done. 
Below
> is my code.
> 
> col <- rep(c("blue", "red", "darkgreen"),
c(16, 16, 16))
> ## Choose different size of points
> cex <- rep(c(1, 1.2, 1), c(16, 16, 16))
> ## Choose the form of the points (square, circle, triangle and
> diamond-shaped
> pch <- rep(c(15, 16, 17), c(16, 16, 16))
> 
> plot(axis1, axis2, main="My plot", xlab="Axis 1",
ylab="Axis 2",
>  col=c(Category, col), pch=pch, cex=cex)
> legend(4, 12.5, c("NorthAmerica", "SouthAmerica",
"Asia"), col = col,
>        pch = pch, pt.cex = cex, title = "Region")
> 
> I also prefer a control on what kind of point I want to use for 
different
> levels of Region. Something like this:
> legend(4,12.5, col(levels(Category), Asia="red",
NorthAmerica="blue",
> SouthAmerica="green"))
So why you do not use Region and/or Category for automatic point 
colouring/size/type.

Without data I can only use built in one.

with(iris, plot(Sepal.Length, Sepal.Width, col= as.numeric(Species)))
legend("topright", legend=levels(iris$Species), pch=19, col=1:3)

Regards
Petr
> 
> Thanks,
> Kumar
> 
>   Region axis1 axis2  NorthAmerica 5 14  NorthAmerica 8 13  NorthAmerica 
8
> 11  NorthAmerica 6 11  NorthAmerica 5 13  SouthAmerica 8 17 SouthAmerica 
7
> 16  SouthAmerica 7 13  SouthAmerica 8 14  SouthAmerica 6 17  Asia 7 13 
Asia
> 6 15  Asia 7 14  Asia 5 13  Asia 4 16
> 
>    [[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.

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Thanks, 

anyway, using build-in R features is preferable for colours

with(data, plot(axis1, axis2, col= c("red", "blue", 
"green")[as.numeric(data$Region)]))
legend("topright", legend=levels(data$Region), fill=
c("red", "blue",
"green"))

although sometimes can be preferable to get advantage of grid graphic

library(ggplot2)
p<-ggplot(data, aes(x=axis1, y=axis2, colour=Region))
p+geom_point()

Regards
Petr
> 
> He provided data, yet in an inconvenient way at the bottom of his post.
> 
> Kumar, please use dput() to provide data to the list, because its much
> easier to import:
> dput(data)    ## name data is made up by me
> 
> structure(list(Region = structure(c(2L, 2L, 2L, 2L, 2L, 3L, 3L, 
> 3L, 3L, 3L, 1L, 1L, 1L, 1L, 1L), .Label = c("Asia",
"NorthAmerica",
> "SouthAmerica"), class = "factor"), axis1 = c(5L, 8L,
8L, 6L,
> 5L, 8L, 7L, 7L, 8L, 6L, 7L, 6L, 7L, 5L, 4L), axis2 = c(14L, 13L, 
> 11L, 11L, 13L, 17L, 16L, 13L, 14L, 17L, 13L, 15L, 14L, 13L, 16L
> )), .Names = c("Region", "axis1", "axis2"),
class = "data.frame",
row.names = c(NA, 
> -15L))
> 
> 
> 
>    [[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide 
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.