[R] color code in loop for piecharts plotting

[Jim Lemon]

On 02/25/2011 09:33 PM, Lucia Rueda wrote:
>
> Hi,
> I am using this loop
>
> par(mfrow=c(3,3))
> annos<-c(2001:2007,2009)
> for (i in annos) {
> t<-subset(masia,YEAR==i)
> t$FAMILIA<-drop.levels(t$FAMILIA)
> pie(table(t$FAMILIA),main=i)
>    }
>
> To make piecharts of species composition among years (my data frame is
> called "masia"). So I get 1 piechart of the families that we have found in
> our survey each year. We don't have always the same families every year so I
> added  t$FAMILIA<-drop.levels(t$FAMILIA)
> to the loop to avoid having those family levels that aren't there in some
> specific years in the pie
>
> The problem is that the color code changes and I get for example different
> colors for the same families in different years.
>
> If I group those families that I have less individuals together in a
> category called "others" and I make a new column called "familia2" with
> fewer levels so that every year I have all levels of familia2 in my species
> composition I don't get the problem and all families have the same color
> among years.
>
> Does anybody know how to avoid the color code change for the families in the
> loop. I know I can do it manually and give each family a color but I have
> quite a lot of families so I'm wondering if there's any way to fix that some
> other way.
>
Hi Lucia,
FAMILIA is probably a factor, therefore can be used as an index with 
as.numeric(). So if you have a vector of colors for all the families in 
your dataset, you could specify the color for each sector of the pie with:

# this gives you different colors for each family
family_colors<-1:length(levels(t$FAMILIA))
for(i in annos) {
  t<-subset(masia,YEAR==i)
  sector_index<-as.numeric(unique(t$FAMILIA))
  pie(table(t$FAMILIA),main=i,col=family_colors[sector_index])
}

Can't try it at the moment, but it should be close.

Jim

[as.numeric(unique(t$FAMILIA[i]))] without dropping the levels (I think).