% Plotting Spilled... Ink?
% Michael Stone
% February 25, 2012

Ever since I bought [Hadley Wickham]'s lovely book ["ggplot2: Elegant Graphics
for Data Analysis (Use R!)"][ggplot2-book] a few weeks back, I've been meaning
to write up a simple end-to-end example of data collection and plotting using
[ggplot2].

Thus, without further delay, let's try to make a pretty picture of the rate at
which I've been writing here (and thus, of the rate at which my rather naive
[site search][site-search] implementation's dataset is growing).

Here's what we'll do:

 1. Install [R] and [ggplot2]:
    
    ~~~~ { .bash }
    sudo aptitude install r-base r-cran-ggplot2
    ~~~~

 2. Collect the data:
    
    ~~~~ { .bash }
    echo date bytes post > data.txt
    (for f in $(find posts -name 'index.txt'); do
      DATE=$(cat $f | head -n 3 | tail -n 1 | sed -e 's/^% //');
      echo $(date -d "$DATE" +%s) \
           $(stat -c '%s' $f) \
           $(echo $f | sed -e 's,posts/,,' -e 's,/index.txt,,');
    done) | sort -n -k1 >> data.txt
    ~~~~

 3. Sanity-check the resulting data:
    
        $ head data.txt
        date bytes post
        1232600400 2038 joy_of_tex
        1234674000 3947 irrefutability
        1275796800 2076 openkey
        1300248000 5958 afd_discussions
        1300593600 1358 safe_phones
        1301371200 1126 convergence
        1302235200 1404 secrets
        1302408000 2916 comment_systems
        1307160000 833 scheduling

 4. Make the plot:
    
        $ R
    
    ~~~~ { .R }
    library("ggplot2")                                      # load ggplot2

    df <- read.table("data.txt", header = TRUE)             # load the data

    ndf <- df[order(df$date),]                              # sort the data
    ndf$date2 <- as.POSIXct(ndf$date, origin="1970-01-01")  # convert timestamps to dates
    ndf$total_bytes <- cumsum(ndf$bytes)                    # count total bytes over time

    svg(filename="data.svg", width=6, height=4)             # make the plot
    qplot(x = date2, y = total_bytes, data=ndf, xlab="date", ylab="total bytes")
    dev.off()
    ~~~~

 5. Enjoy:
    
    ![](data.svg)

(P.S. - Care to guess when I joined [Iron Blogger]? :-)

[Hadley Wickham]: http://had.co.nz/
[R]: http://www.r-project.org
[ggplot2]: http://had.co.nz/ggplot2/
[ggplot2-book]: http://www.amazon.com/gp/product/0387981403?ie=UTF8&tag=hadlwick-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=0387981403
[site-search]: http://mstone.info/posts/site_search/
[Iron Blogger]: http://iron-blogger.mako.cc/