mages' blog

Version 0.5.6 of googleVis was released on CRAN over the weekend. This version fixes a bug in gvisMotionChart. Its arguments xvar, yvar, sizevar and colorvar were not always picked up correctly.

Thanks to Juuso Parkkinen for reporting this issue.

Example: Love, or to love

A few years ago Martin Hilpert posted an interesting case study for motion charts. Martin is a linguist and he researched how the usage of words in American English changed over time, e.g. some words were more often used as nouns in the past and then became more popular as a verb. Do you talk about love, or do you tell someone that you love her/him? Visit his motion chart web page for more information and details!

R code

Session Info

R version 3.1.1 (2014-07-10)
Platform: x86_64-apple-darwin13.1.0 (64-bit)

locale:
[1] en_GB.UTF-8/en_GB.UTF-8/en_GB.UTF-8/C/en_GB.UTF-8/en_GB.UTF-8

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods  
[7] base     

other attached packages:
[1] googleVis_0.5.6

loaded via a namespace (and not attached):
[1] RJSONIO_1.3-0 tools_3.1.1

A new version of googleVis has been released on CRAN and the project site. Version 0.2.16 adds the functionality to plot quarterly and monthly data as a motion chart.

To illustrate the new feature I looked for a quarterly data set and stumbled across the quarterly UK house price data published by Nationwide, a building society. The data is available in a spread sheet format and presents the average house prices and indexed to 100 in Q1 1993 by region in the UK from Q4 1973 to Q1 2012. Unfortunately the data is formated for human eyes rather than for computers, see the screen shot below.

Screen shot of Nationwide's UK house price data in Excel

Never-mind, the XLConnect package by Mirai Solutions does a fabulous job in reading Excel files into R. An advantage of XLConnect, compared to other packages, is that it also works on a Mac, although I had to install the package from source (install.packages("XLConnect", type="source")).

Following on from my article about accessing and plotting World Bank data with R I want to talk about how to change the initial view of a motion chart.

Over the last couple of weeks I have been asked a view times how to do this. For instance Stephen O'Grady wanted to create a motion chart, which shows initially a line chart, rather than a bubble chart.

Changing the initial settings of a motion chart is actually quite easy, if you know how to. The trick is to use the state argument in the list of options of gvisMotionChart.

As a case study I will use the World Bank data set and try to do some homework given by Duncan Temple Lang in his course on introduction to statistical computing course. Duncan asked his students to query the World Bank data base to create a line chart, which would show the number of internet users per 1000 in Africa over time. Further, he would like to see a legend next to the chart to identify which country is which and tooltips for each curve to identify the country.

A motion chart, displayed as a line chart, would do the trick.

Okay, getting the data is easy, thanks to the WDI package, or via a direct download, and so it is to create a motion chart with bubbles. Interactively I can change the bubble chart into a line chart, I can select some countries and change the y-axis to log-scale. However, when I reload the page I am back to square one: a bubble chart. So the idea is to pass the changed chart settings on to the initial plot. I find those settings, of the current view, as a string in the advanced tab of the settings window. I click on the wrench symbol in the bottom right hand corner of a motion chart to access this window.

Screen shot the settings window of a motion chart

Next I copy this string and paste it into the state argument of the options list. Note the line break at the beginning and at the end of the state string in the example. Alternatively I can add \n to both side of the state string.

Here is an example, where I pre-selected Sierra Leone and Seychelles (countries with the lowest and highest number of internet users) together with Africa, North Africa and Sub-Saharan Africa (all income levels). You find the R code below to replicate the plot.

What does the data tell you? Play around with the graph, e.g. change it to a column graph, deselect all countries and change the y-axes to linear again, and hit the play button. How could we improve the plot?

Over the past couple of days I played around with the data sets of the World Bank, and I have to admit that I am blown away by it. It is amazing, to see what is available on their web site and it is worth visiting their Data Visualisation Tools page. It is fantastic that they provide an API to their data. They have used it to build an iPhone App which is pretty cool. You can have the world's data in your pocket.

In this post I will show you how we can access data from the World Bank in R. As an example we create a motion chart, in the Hans Rosling style, as you find it on the Google Public Data Explorer site, which also uses data from the World Bank. Doing this, should give us the confidence that we understand the World Bank's interface. You can find this example as demo WorldBank as part of the googleVis package from version 0.2.10 onwards.

So let's try to replicate the initial plot of the Google Public Data Explorer, which shows fertility rate against life expectancy for each country from 1960 to today, whereby the countries are represented as bubbles, with the size reflecting the population and the colour the region.