C REATING FANCY MAPS AND PIE CHARTS USING G OOGLE API CHARTS Lionel Page and Franz Buscha Centre for Employment Research.

CREATING FANCY MAPS AND PIE CHARTS USING GOOGLE API CHARTS

Lionel Page and Franz Buscha

Centre for Employment Centre for Employment ResearchResearch

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]

Google-o-meter

Chart colors Yes Yes Yes Yes Yes Yes Yes YesSolid fill

Yes Yes Yes Yes Yes Yes Background only

Background only

Data scaling Yes Yes Yes Yes Yes Yes YesLinear gradient Yes Yes Yes Yes Yes

Background only

Linear stripesYes Yes Yes Yes Yes

Background only

Chart title Yes Yes Yes Yes Yes YesChart legend

Yes Yes Yes Yes Yes

Multiple axis labels Yes Yes Yes Yes

Grid lines Yes Yes Yes YesShape markers Yes Yes Yes Yes

Horizontal range markers

Yes Yes Yes Yes

Vertical range markers

Yes Yes Yes Yes

Line styles Yes Yes YesFill area Yes Yes YesBar width and spacing Yes

Bar chart zero line Yes

Pie chart and Google-o-meter labels Yes Yes

Pie chart MapsParameter Bar chart Line and Sparkline chart

Radar chart

Scatter plot

Venn diagram

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:

gmap location statevar valuevar {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

EXAMPLE OF GMAP The following picture will be saved in your local

directory

gmap usa states value, color(yellow green) graph h(100) w(200)

EXAMPLE OF GMAP

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 gpie which allows users to create 3

dimensional pie charts

In its current state (v1.0) gpie accepts the following command line:

gpie labelvar valuevar {if} [, color(#) dim2 graph file(filename)]

EXAMPLE OF GPIE

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 findit tmap (Pisati, 2004, SJ) for more

complicated thematic mapping futures using Stata’s graphics engine