R help - Sep 2009 - Color of the plot which correspond to the group of the observations

Dear All,
?
Let:

dp: depth of the river
tp: temperature with respect to depth

These pair of observations are in 3 different groups i.e:
Obs. 1,3,5,7?from the first group
Obs. 2,4 and?10?from second group
Obs 6,8 and 9?from third group.

We can have a simple scatter plot, between depth as y-axis and temperature as
x-axis, with each pairs are denoted by a red dot, by using a plot function shown
below.
?
#####################
?dp <- c(1,4,3,2,5,7,9,8,9,2)
?tp <- 1:10
?plot(tp,dp, type= 'p', col = 'red')
?#####################

Could someone?please give some?advices on the way??to have a plot in which the
color of each?pair of observation corrrespond to?its group? For instance, we
might have red, blue and green dots corresponding to groups 1,2 and 3,
respectively.?


Thank you
Fir

It is easier in lattice

dp <- c(1,4,3,2,5,7,9,8,9,2)
tp <- 1:10
gg <- rep(1:3, c(3,3,4))
ddff <- data.frame(dp=dp, tp=tp, gg=gg)
xyplot(dp ~ tp, groups=gg, data=ddff)

Try these three options,


 dp <- c(1,4,3,2,5,7,9,8,9,2)
 tp <- 1:10
 group <- factor(c(1, 2, 1, 2, 1, 3, 1, 3, 3, 2), label=letters[1:3])

plot(tp,dp, type= 'p', col = group)

d <- data.frame(dp=dp, tp=tp, group=group)

library(lattice)
 xyplot(dp~tp, data=d, groups=group, auto.key=TRUE)

library(ggplot2)
qplot(tp, dp, data=d, colour=group)

HTH,

baptiste


2009/9/24 FMH <kagba2006 at yahoo.com>:
> Dear All,
>
> Let:
>
> dp: depth of the river
> tp: temperature with respect to depth
>
> These pair of observations are in 3 different groups i.e:
> Obs. 1,3,5,7?from the first group
> Obs. 2,4 and?10?from second group
> Obs 6,8 and 9?from third group.
>
> We can have a simple scatter plot, between depth as y-axis and temperature
as x-axis, with each pairs are denoted by a red dot, by using a plot function
shown below.
>
> #####################
> ?dp <- c(1,4,3,2,5,7,9,8,9,2)
> ?tp <- 1:10
> ?plot(tp,dp, type= 'p', col = 'red')
> ?#####################
>
> Could someone?please give some?advices on the way??to have a plot in which
the color of each?pair of observation corrrespond to?its group? For instance, we
might have red, blue and green dots corresponding to groups 1,2 and 3,
respectively.
>
>
> Thank you
> Fir
>
>
>
>
> ______________________________________________
> R-help at r-project.org mailing list
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> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

On 09/25/2009 04:28 AM, FMH wrote:
> Dear All,
>   
> Let:
>
> dp: depth of the river
> tp: temperature with respect to depth
>
> These pair of observations are in 3 different groups i.e:
> Obs. 1,3,5,7 from the first group
> Obs. 2,4 and 10 from second group
> Obs 6,8 and 9 from third group.
>
> We can have a simple scatter plot, between depth as y-axis and temperature
as x-axis, with each pairs are denoted by a red dot, by using a plot function
shown below.
>   
> #####################
>   dp<- c(1,4,3,2,5,7,9,8,9,2)
>   tp<- 1:10
>   plot(tp,dp, type= 'p', col = 'red')
>   #####################
>
> Could someone please give some advices on the way  to have a plot in which
the color of each pair of observation corrrespond to its group? For instance, we
might have red, blue and green dots corresponding to groups 1,2 and 3,
respectively.
>    
Hi Fir,
You can do it manually like this:

plot(tp,dp,type="p",col=c("red","blue","red","blue","red","green",
  "red","green","green","blue"))

but it is a lot easier if there is a variable that identifies which 
group contains each observation:

obs.group<-c(1,2,1,2,1,3,1,3,3,2)
plot(tp,dp,type="p",col=c("red","blue","green")[obs.group])

If you want the color to be scaled to one of the variables:

plot(tp,dp,type="p",
  col=color.scale(tp,extremes=c("blue","red")))

Jim