How to display date format (Sep-12) in bar chart and set y axis limit?

Question

I have two questions on building a bar plot by using ggplot().

How to display data format (Sep-12)?

I would like to display the date in the format of Sep-12. My data is a quarterly summary. I would like to show Mar, Jun, Sep and Dec quarters. However, I used the as.Date(YearQuarter) within the ggplot() function. It shows a different sequence of Apr, July, Oct, Jan.

How to increase y axis limit?

The y axis is set at 70%, one of value label is out of the picutre. I have added ylim(0,1) to increase the y limit to 1. However, I lost the percentage format as the y axis is not displaying the percentage anymore.

x4.can.t.m <- structure(list(NR_CAT = structure(c(1L, 2L, 3L, 1L, 2L, 3L, 1L, 
2L, 3L, 1L, 2L, 3L, 1L, 2L, 3L, 1L, 2L, 3L, 1L, 2L, 3L, 1L, 2L, 
3L, 1L, 2L, 3L, 1L, 2L, 3L, 1L, 2L, 3L, 1L, 2L, 3L, 1L, 2L, 3L, 
1L, 2L, 3L, 1L, 2L, 3L), .Label = c("0%", "1 to 84%", "85% +"
), class = "factor"), TYPE = structure(c(1L, 1L, 1L, 2L, 2L, 
2L, 3L, 3L, 3L, 1L, 1L, 1L, 2L, 2L, 2L, 3L, 3L, 3L, 1L, 1L, 1L, 
2L, 2L, 2L, 3L, 3L, 3L, 1L, 1L, 1L, 2L, 2L, 2L, 3L, 3L, 3L, 1L, 
1L, 1L, 2L, 2L, 2L, 3L, 3L, 3L), .Label = c("PM BUSINESS", "PM CONSUMER", 
"PREPAY"), class = "factor"), YearQuarter = structure(c(1L, 1L, 
1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 4L, 4L, 4L, 4L, 4L, 4L, 4L, 
4L, 4L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L, 5L), .Label = c("2011-09-01", 
"2011-12-01", "2012-03-01", "2012-06-01", "2012-09-01"), class = "factor"), 
    value = c(0.5, 0, 0.5, 0.35, 0, 0.65, 0.28, 0.02, 0.7, 0.4, 
    0, 0.6, 0.38, 0, 0.62, 0.43, 0.01, 0.56, 0.57, 0, 0.43, 0.35, 
    0, 0.65, 0.39, 0.01, 0.6, 0.55, 0, 0.45, 0.4, 0.02, 0.58, 
    0.35, 0.02, 0.63, 0.35, 0, 0.65, 0.55, 0.01, 0.44, 0.47, 
    0, 0.53)), .Names = c("NR_CAT", "TYPE", "YearQuarter", "value"
), row.names = c(NA, -45L), class = "data.frame")

This is my plot code:

x4.can.t.m$YearQuarter <- as.Date(x4.can.t.m$YearQuarter)
x4.can.t.d.bar <- ggplot(data=x4.can.t.m, aes(x=YearQuarter, y=value,fill=NR_CAT)) + 
                  geom_bar(stat="identity",position = "dodge",ymax=NR_CAT+0.2) +
              facet_wrap(~TYPE,ncol=1) +
                  geom_text(aes(label =paste(round(value*100,0),"%",sep="")), 
                             position=position_dodge(width=0.9), 
                             vjust=-0.25,size=3)  +
        scale_y_continuous(formatter='percent',ylim=1) +
            labs(y="Percentage",x="Year Quarter") +
            ylim(0,100%)


x4.can.t.d.bar +scale_fill_manual("Canopy Indicators",values=tourism.cols(c(6,9,8)))+
                opts(title="Canopy Indicator: All Customers portout for Network 
                            Issues",size=4)

Answer 1

It looks like you have an older version of ggplot; the following is for ggplot 0.2.9.1. I had to fix several things to make your plot work. Starting from your original definition of x4.can.t.m:

x4.can.t.m$YearQuarter <- format(as.Date(x4.can.t.m$YearQuarter),"%b-%y")

library("scales")
ggplot(data=x4.can.t.m, aes(x=YearQuarter, y=value, fill=NR_CAT)) + 
  geom_bar(stat="identity", position = "dodge") +
  geom_text(aes(label = paste(round(value*100,0),"%",sep=""), group=NR_CAT), 
            position=position_dodge(width=0.9), 
            vjust=-0.25, size=3)  +
  scale_y_continuous("Percentage", labels=percent, limits=c(0,1)) +
  labs(x="Year Quarter") +
  scale_fill_discrete("Canopy Indicators") + 
  facet_wrap(~TYPE,ncol=1) +
  ggtitle("Canopy Indicator: All Customers portout for Network Issues") +
  theme(plot.title = element_text(size=rel(1.2)))

The first part of the question is just achieved by formatting YearQuarter into the format you wanted, leaving it as a string.

The second part specifies the limits in scale_y_continuous and uses the labels argument to specify the formatting function. Note that library("scales") is needed for this part to work.