How to plot an histogram with y as a sum of the x values for every bin in ggplot2

Question

I have a pv dataframe containing information regarding solar plants. One variable is the generation power in kw:

id   power
1    20.1
2    110.1
3    3.0
4    2         


        

Answer 1

This should do what you want:

set.seed(1)
df <- data.frame(id=1:100, power=rlnorm(100, log(100)))
ggplot(df) + 
  geom_histogram(aes(x=power, weight=power), binwidth=50) +
  ylab("Total Power (kW)")

The weight aesthetic forces the stat calculation to multiply each count by the corresponding weight, which in this case is equivalent to summing the power values.

And here is a better visualization:

ggplot(transform(df, power.bin=cut(power, 0:24 * 50, include.lowest=TRUE))) + 
  geom_bar(aes(x=power.bin, y=power), color="white", position="stack", stat="identity") +
  ylab("Total Power (kW)") + 
  scale_x_discrete(drop=F) +
  theme(axis.text.x=element_text(angle=90, vjust=.5, hjust=1))