Internet-Defense-League

2010-02-25

inkblot: an alternative to stacked bar graphs

Sometimes it is not easy to get useful information from a stacked bar chart, see for instance
this blogpost at Support Analytics.

So-called inkblot charts, as discussed at Kaiser Fung's
Junk Charts, allow the reader to focus on the evolution
of a time series.

Now how to make this kind of charts with R? I asked on
StackOverflow. The given answers led to an implementation
of an inkblot function. It is delivered with the wzd package on r-forge. Here is an example which visualizes the income per capita from
various countries, as reported by gapminder:


> #install.packages("wzd")
> library(wzd)
> data(gmIncomePerCapita)
> selection <- window(gmIncomePerCapita,
+ start=as.Date("1900-01-01"),
+ end=as.Date("2008-01-01")
+ )[,c("Germany", "India", "Japan", "Norway", "United States", "Venezuela")]
> inkblot(selection, min.height=1300)


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