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Centre for Employment Research. Creating fancy maps and pie charts using Google API charts. Lionel Page and Franz Buscha. Introduction. These ado files use Stata’s ability to easily interface with the internet and contact: chart.apis.google.com
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Centre for Employment Research Creating fancy maps and pie charts using Google API charts Lionel Page and Franz Buscha
Introduction • These ado files use Stata’s ability to easily interface with the internet and contact: chart.apis.google.com • Google chart API (Application Programming Interface) allows users to dynamically create charts and maps by sending a pre-programmed URL to Google • Google then returns a PNG-image which, with a bit of luck, is a useable piece of information!
Google charts API • Stata’s unique and powerful data-management abilities make it a good complement in order to pre-format data and then send it to Google and allow it to compile this data into a different array of graphs/figures. • How does Google API work? http://chart.apis.google.com/chart?chs=250x100 [size]&chd=t:60,40 [data]&cht=p3 [type]&chl=Hello|World[labels]
GMAP • Here we present gmap which allows users to create .png using Google API chart In its current state (v1.1) gmap accepts the following command line: gmaplocation statevarvaluevar{if} [, color(# [#]) graph file(filename)] Width(numlist) Height(numlist)] The parameter location can take the following values: africa, asia, europe, middle_east, south_america, usa, world. For each specific region, statevar must contain the States' identifiers from the list of codes from Google.
Example of GMAP • The following picture will be saved in your local directory gmapusa states value, color(yellow green) graph h(100) w(200)
Considerations • Only have 1 colour gradient at the moment • Different shades of one colour • Transition from one colour to another • Google allows multiple gradients • I.e, from green to black to red • This ‘should’ allow specific colours across regions • E.g. Cons/Labour/Libdems (Blue, Red, Yellow) • v.1.2
GPIE • Here we present gpiewhich allows users to create 3 dimensional pie charts In its current state (v1.0) gpieaccepts the following command line: gpielabelvarvaluevar {if} [, color(#) dim2 graph file(filename)]
Example of GPIE • The following picture will be saved in your local directory:. Alternatively, gpie label values, color(yellow) dim2
Useage and Limitations • Google API charts is aimed at web-based developments such as blogs and websites and therefore offers little in terms statistical analysis • gmap should be seen as a informational and explorative tool • Limited to 250,000 API calls per day • No labels! • Maximum picture size is 440x220 pixels • Country labels must be in ISO 3166-1-alpha-2 code • Only United States supports state level mapping • Please findittmap(Pisati, 2004, SJ) for more complicated thematic mapping futures using Stata’s graphics engine