[R] ggplot2 stacked bar - sum of values rather than count

[J Toll]

On Mon, Jan 16, 2012 at 1:13 AM, Paul <paul at paulhurley.co.uk> wrote:
> On 16/01/12 02:08, J Toll wrote:
>> Hi,
>>
>> I'm trying to create a stacked bar plot using ggplot2. Rather than
>> plotting the count of each of the 13 "Bar" factors on the Y axis, I
>> would like to represent the sum of the Values associated with each of
>> the 13 "Bar" factors. Is there a way to do that?  Given the following
>> data, that would obviously mean that there would be some negative sums
>> represented.  Here's a bit of example data along with the command I've
>> been using.
>>
>>> library(ggplot2)
>>> x
>>           Value Bar Segment
>> 1   1.10020075   1       1
>> 2 -1.37734577   2       1
>> 3   2.50702876 3       1
>> 4 0.58737028   3       2
>> 5   0.21106851   3       3
>> 6  -2.50119261   4       1
>> 7 1.34984831   5       1
>> 8 -0.27556149   6       1
>> 9 -1.54401647   6       2
>> 10 -2.75975562   6       3
>> 11 -0.09527123   6       4
>> 12 1.36331646   7       1
>> 13 -0.36051429   8       1
>> 14 1.36790999   9       1
>> 15 0.15064633   9       2
>> 16 0.34022421   9       3
>> 17 -0.64512970  10       1
>> 18 0.83268199  11       1
>> 19 -1.50117728  12       1
>> 20  1.09004959  13       1
>>> qplot(factor(Bar), data = x, geom = "bar", fill = factor(Segment))
>> Thanks for any suggestions you might have.
>>
>> James
>>
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>> and provide commented, minimal, self-contained, reproducible code.
> I'm not at my usual computer, but in ggplot2 the geom_bar geom is
> designed for stats, so by default does report count.  You can change the
> stat method (ie to identity to just use the values in the column) but
> the easiest (IIRC) is to give a weight;
>
> #Gives count
> ||
>
> qplot  <http://had.co.nz/ggplot2/qplot.html>(color,  data=diamonds,  geom="bar")
>
> #Gives sum of carat variable
> qplot  <http://had.co.nz/ggplot2/qplot.html>(color,  data=diamonds,  geom="bar",  weight=carat,  ylab="carat")
>
> #just gives raw values from meanprice column
> ||
>
> qplot  <http://had.co.nz/ggplot2/qplot.html>(cut,  meanprice,  geom="bar",  stat="identity")
>
> Check out the ggplot2 help page (http://had.co.nz/ggplot2/geom_bar.html) for more info.
>
> Regards,
>
> Paul.
>


Paul,

Thank you for the help.  Using your second example, I added "weight =
Value" to my previous command to get the chart I wanted.

qplot(factor(Bar), data=x, geom="bar", weight = Value, fill=factor(Segment))

ggplot2 issues a warning message with my data because it has negative values:
"Warning message:
Stacking not well defined when ymin != 0 "

But that's not a real concern.

Anyway, thanks again for your help.


James