[R] barplot that displays sums of values of 2 y colums grouped by different variables

Eric Berger ericjberger at gmail.com
Mon Jan 15 20:34:30 CET 2018

'position="dodge"' has no effect in the plot because the x-axis is a factor
variable. The bars do not need to be moved to avoid each other. The
'aes(fill=y)' is specifying that you want the color gradient to capture the
sums in the 'y' variable. You might be better off to use 'no' and 'yes'
rather than 'n' and 'y' to avoid confusion. Then you would see that the
statement would be 'aes(fill=yes)'. Summary: the height of each bar
represents the sum of the 'no' for that city, and the color of each bar
represents the sum of the 'yes' for that city. Your code is fine, unless
that is not what you were trying to do.


On Mon, Jan 15, 2018 at 6:59 PM, kenneth dyson <kenneth at kidscodejeunesse.org
> wrote:

> I am trying to create a barplot displaying the sums of 2 columns of data
> grouped by a variable. the data is set up like this:
> "city" "n" "y" <br>
> mon 100 200 <br>
> tor 209 300 <br>
> edm 98 87 <br>
> mon 20 76 <br>
> tor 50 96 <br>
> edm 62 27 <br>
> the resulting plot should have city as the x-axis, 2 bars per city, 1
> representing the sum of "n" in that city, the other the sum of "y" in that
> city.
> If possible also show the sum in each bar as a label?
> I aggregated the data into sums like this:
> sum_data <- aggregate(. ~ City,data=raw_data,sum)
> this gave me the sums per city as I wanted but for some reason 1 of the
> cities is missing in the output.
> Using this code for the plot:
> ggplot(sum_data,aes(x = City,y = n)) + geom_bar(aes(fill = y),stat =
> "identity",position = "dodge")
> gave be a bar plot with one bar per city showing the sum of y as a color
> gradient. not what I expected given the "dodge" command in geom_bar.
> Thanks.
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