R help - Mar 2011 - proportional symbol map ggplot

Hello,

we want to plot a proportional symbol map with ggplot. Symbols' area should 
have the same proportions as the scaled variable.
Hereby an example we found on 
http://www.r-bloggers.com/bubble-chart-by-using-ggplot2/ . In this example 
we see the proportions of the symbols' area are different from the 
proportions of the scaled variable:

crime <- 
read.csv("http://datasets.flowingdata.com/crimeRatesByState2008.csv", 
header=TRUE, sep="\t")
p <- ggplot(crime, aes(murder,burglary,size=population, label=state))
p <- p+geom_point(colour="red")
+scale_area(to=c(1,20))+geom_text(size=3)

Example:
proportion population Pennsylvania/Tennessee= 2.003
proportion symbols' area Pennsylvania/Tennessee= +/- 2.50

proportion population California/Florida= 2.005
proportion symbols' area California/Florida= +/-2.25

What we would like is that the proportion of the symbols' area is also equal
to 2.0.

We see the same in the legend:
proportion population 1.6e+07 / 4.0e+06 = 4.0
proportion symbols' area 1.6e+07 / 4.0e+06= +/-5.0


Thanks in advance!

Ann Frederix
Robbie Heremans

Hello Scott,

Thank you for the tips (I have posted the issue on the google group too), but
there's nothing on these or other websites that gives an answer on our
question.
Following the traditional used rules of making a symbol plot, the used symbols
should have the same proportions, based on area, then the values have.
Unfortunately, this is not so in the plots we make with the code below
(scale_area).


Yours sincerely,

Ann Frederix

----- Original Message ----- 
  From: Scott Chamberlain 
  To: Strategische Analyse CSD Hasselt 
  Sent: Monday, March 14, 2011 4:05 PM
  Subject: Re: [R] proportional symbol map ggplot


  There is a ggplot2 google groups mailing list that you may get more
appropriate help from:


  http://groups.google.com/group/ggplot2?pli=1


  and the ggplot2 website is very helpful
  http://had.co.nz/ggplot2/
  On Monday, March 14, 2011 at 9:41 AM, Strategische Analyse CSD Hasselt wrote:

    Hello,

    we want to plot a proportional symbol map with ggplot. Symbols' area
should
    have the same proportions as the scaled variable.
    Hereby an example we found on 
    http://www.r-bloggers.com/bubble-chart-by-using-ggplot2/ . In this example 
    we see the proportions of the symbols' area are different from the 
    proportions of the scaled variable:

    crime <- 
   
read.csv("http://datasets.flowingdata.com/crimeRatesByState2008.csv",
    header=TRUE, sep="\t")
    p <- ggplot(crime, aes(murder,burglary,size=population, label=state))
    p <- p+geom_point(colour="red")
+scale_area(to=c(1,20))+geom_text(size=3)

    Example:
    proportion population Pennsylvania/Tennessee= 2.003
    proportion symbols' area Pennsylvania/Tennessee= +/- 2.50

    proportion population California/Florida= 2.005
    proportion symbols' area California/Florida= +/-2.25

    What we would like is that the proportion of the symbols' area is also
equal
    to 2.0.

    We see the same in the legend:
    proportion population 1.6e+07 / 4.0e+06 = 4.0
    proportion symbols' area 1.6e+07 / 4.0e+06= +/-5.0


    Thanks in advance!

    Ann Frederix
    Robbie Heremans

    ______________________________________________
    R-help@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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On Mon, Mar 14, 2011 at 9:41 AM, Strategische Analyse CSD Hasselt
<csd.sa at fedpolhasselt.be> wrote:
> Hello,
>
> we want to plot a proportional symbol map with ggplot. Symbols' area
should
> have the same proportions as the scaled variable.
> Hereby an example we found on
> http://www.r-bloggers.com/bubble-chart-by-using-ggplot2/ . In this example
> we see the proportions of the symbols' area are different from the
> proportions of the scaled variable:
>
> crime <-
>
read.csv("http://datasets.flowingdata.com/crimeRatesByState2008.csv",
> header=TRUE, sep="\t")
> p <- ggplot(crime, aes(murder,burglary,size=population, label=state))
> p <- p+geom_point(colour="red")
+scale_area(to=c(1,20))+geom_text(size=3)
>
> Example:
> proportion population Pennsylvania/Tennessee= 2.003
> proportion symbols' area Pennsylvania/Tennessee= +/- 2.50
>
> proportion population California/Florida= 2.005
> proportion symbols' area California/Florida= +/-2.25
>
> What we would like is that the proportion of the symbols' area is also
equal
> to 2.0.
To do that you need to make sure the lower limit extends to 0 and the
size of the smallest circle is also 0. I think something like
scale_area(to=c(0, 20), limits = c(0, 4e7), breaks = 1:4 * 1e7) should
suffice.

It would also be helpful if you stated how you calculated the areas.

Hadley

-- 
Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University
http://had.co.nz/