Transcript Slide 1

Centre for Employment
Research
CREATING FANCY MAPS AND PIE CHARTS
USING GOOGLE API CHARTS
Lionel Page and Franz Buscha
INTRODUCTION
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These ado files use Stata’s ability to easily interface with
the internet and contact:
chart.apis.google.com
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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
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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]
Parameter
Bar chart
Chart colors
Solid fill
Yes
Line and
Sparkline
chart
Yes
Yes
Data scaling
Linear
gradient
Linear stripes
Chart title
Chart legend
Multiple axis
labels
Grid lines
Shape
markers
Horizontal
range
markers
Vertical
range
markers
Line styles
Fill area
Bar width
and spacing
Bar chart
zero line
Pie chart and
Google-ometer labels
Radar
chart
Scatter
plot
Venn
diagram
Pie chart
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Googleo-meter
Maps
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GMAP
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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
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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
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Only have 1 colour gradient at the moment
Different shades of one colour
 Transition from one colour to another
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Google allows multiple gradients
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This ‘should’ allow specific colours across regions
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I.e, from green to black to red
E.g. Cons/Labour/Libdems (Blue, Red, Yellow)
v.1.2
GPIE
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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
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The following picture will be saved in your local directory:.
Alternatively,
gpie label values, color(yellow) dim2
USEAGE AND LIMITATIONS
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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