r - Population pyramid plot with ggplot2 and dplyr (instead of plyr)

Question

I am trying to reproduce the simple population pyramid from the post Simpler population pyramid in ggplot2

using ggplot2 and dplyr (instead of plyr).

Here is the original example with plyr and a seed

set.seed(321)
test <- data.frame(v=sample(1:20,1000,replace=T), g=c('M','F'))

require(ggplot2)
require(plyr)    
ggplot(data=test,aes(x=as.factor(v),fill=g)) + 
  geom_bar(subset=.(g=="F")) + 
  geom_bar(subset=.(g=="M"),aes(y=..count..*(-1))) + 
  scale_y_continuous(breaks=seq(-40,40,10),labels=abs(seq(-40,40,10))) + 
  coord_flip()

Works fine.

But how can I generate this same plot with dplyr instead? The example uses plyr in the subset = .(g == statements.

I have tried the following with dplyr::filter but got an error:

require(dplyr)
ggplot(data=test,aes(x=as.factor(v),fill=g)) + 
  geom_bar(dplyr::filter(test, g=="F")) + 
  geom_bar(dplyr::filter(test, g=="M"),aes(y=..count..*(-1))) + 
  scale_y_continuous(breaks=seq(-40,40,10),labels=abs(seq(-40,40,10))) + 
  coord_flip()

Error in get(x, envir = this, inherits = inh)(this, ...) : 
  Mapping should be a list of unevaluated mappings created by aes or aes_string

Answer 1

You avoid the error by specifying the argument data in geom_bar:

ggplot(data = test, aes(x = as.factor(v), fill = g)) + 
  geom_bar(data = dplyr::filter(test, g == "F")) + 
  geom_bar(data = dplyr::filter(test, g == "M"), aes(y = ..count.. * (-1))) + 
  scale_y_continuous(breaks = seq(-40, 40, 10), labels = abs(seq(-40, 40, 10))) + 
  coord_flip()