Month-Year bar graph plot faceted and filled on year; with data input as date in char format

Question

Environment: Win 7 HP, R v2.15.1

What I wish to get to:

• Plot y (numeric) vs x (date) with
• labels month-year abbrev, sorted mon+year, las2 vertically aligned
• colours filled by year
• facet-grid by year

I have tried different approaches after reading up different threads in this forum, but unable to get what I need. Need help. Attaching sample data and results.

MySample Data

x <- c("04-01-10","05-01-10","06-01-10","07-01-10","08-01-10","09-01-10","10-01-10","11-01-10","12-01-10","01-01-11","02-01-11","03-01-11","04-01-11","05-01-11","06-01-11","07-01-11","08-01-11","09-01-11","10-01-11","11-01-11","12-01-11","01-01-12","02-01-12","03-01-12","04-01-12","05-01-12","06-01-12")
y <- c(120,210,130,160,190,210,80,70,110,120,140,160,130,200,110,180,210,200,90,60,100,100,120,170,100,180,120)

x is date (character) in mm-dd-yy format tz:IST (Calcutta / Asia) data has only single y value per month which is on the start date of the month

Convert to Data Frame

MySample <- data.frame(x) ## convert to dataframe 
MySample$y <- y

load required libraries

require(lubridate) 
require(ggplot2)

MySample Base Plot

1) Plot x vs y

    ggplot(MySample, aes(MySample$x, MySample$y)) + 
        geom_bar(y=MySample$y,stat="identity") 

Gave me base plot results

2) Plot x vs y + fill=year

    ggplot(MySample, aes(MySample$x, MySample$y, fill=year(MySample$x))) + 
        geom_bar(y=MySample$y,stat="identity")

gave me fills but have 5 fill years with 2010,2010.5,2011,2011.5,2012

I have tried different approaches but running into one error or another.

3) Plot x vs y + fill=year + facet_grid(year)

    ggplot(MySample, aes(x, y, fill=year(x))) + 
        geom_bar(y=MySample$y,stat="identity") + 
        facet_grid(. ~ year(MySample$x)) 

Get : Error in layout_base(data, cols, drop = drop) : At least one layer must contain all variables used for facetting

4) Plot x vs y + fill=year + facet_grid(year) + labels-month (abbr)

    ggplot(MySample, aes(x, y, fill=year(x))) + 
        geom_bar(y=MySample$y,stat="identity") + 
        scale_x_date(labels=month(MySample$x,label=TRUE,abbr=TRUE))

Get : Error in scale_labels.continuous(scale, major) : Breaks and labels are different lengths

I'm stuck and need help to move forward. Need solutions to address the following requirements:

1. 3 fill years only - 2010,2011,2012
2. xlabels - %b%y format; sorted on month-year sequence; las2 positioned (vertical)
3. facet_grid by year with only that year's xlabels and bars in the appropriate facet-grid

Answer 1

To answer your 3 points:

1. use scale_fill_gradient(breaks=unique(MySample$year))
2. use the standard built-in date system instead of lubridate. you can specify the format in ggplot2 with date_format.
3. use: +facet_grid(. ~ year, scales = "free")

The following code will do it:

MySample$date <- as.Date(MySample$x, "%m-%d-%y")
MySample$year <- year(MySample$date)

ggplot(MySample, aes(date, y, fill = year)) + 
  geom_bar(y=y,stat="identity") + 
  facet_grid(. ~ year, scales = "free") +
  scale_x_date(labels = date_format("%b/%y")) +
  scale_fill_gradient(breaks=unique(MySample$year))