ggplot2在连续条形图上出现级别问题

Question

I have a dataset that looks something like this:

testSet <- data.table(date=as.Date(c("2013-07-02","2013-08-03","2013-09-04",
                                     "2013-10-05","2013-11-06")), 
                      yr = c(2013,2013,2013,2013,2013), 
                      mo = c(07,08,09,10,11), 
                      da = c(02,03,04,05,06), 
                      plant = LETTERS[1:5], 
                      product = letters[26:22], 
                      rating = runif(5))

What I would like to do is plot 2 graphs using ggplot2 .

The first would give me a dodged, continuous bar chart for all months that would have the product on the x , the ratings on the y , and the dates grouped and plotted on their respective products.

x = product

y = rating

Dodge = date

The second that I'm trying to create is a dodged, continuous bar chart for one month that would have the plant on the x, the ratings on the y, and the product grouped and plotted on their respective plants.

x = plant

y = rating

Dodge = product

I'm looking for an output that is very similar to this: http://docs.ggplot2.org/0.9.3/geom_bar-28.png but continuous.

I've had issues trying to figure out how the levels things works and haven't seen an example of a dodged, continuous chart.

Here is the code I have created so far:

testMean <- tapply(testSet$rating, list(testSet$mo), mean)

testLevels <- factor(levels(testSet$product,testSet$mo), 
                  levels = levels(testSet$product,testSet$mo))

qplot(testLevels, aes(testMean, fill=cut)) +
          geom_bar(position="dodge", stat="identity")

This is what the ggplot2 site says about creating a continuous bar chart, but it doesn't say anything about how to do it with multiple graphs overlayed on top of each other and then dodged, like in the one I linked to earlier. Here is their code:

meanprice <- tapply(diamonds$price, diamonds$cut, mean)

cut <- factor(levels(diamonds$cut), levels = levels(diamonds$cut))
qplot(cut, meanprice)

I appreciate the help, guys!

Answer 1

I ended up using the diamonds built in data set to get my question answered. All the thanks in the world to @carloscinelli for his assistance.

library(data.table)
data <- data.table(diamonds)[,list(mean_carat=mean(carat)), by=c('cut', 'color')]

Thanks!