Category Archives: Maps

Tutorial on Mapping

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Introduction

What do you want to map? There are a variety of maps and a variety of methods.

choropleth 1

These are color gradient maps. A simple method is to use IBM’s Many Eyes online software to do a graph by state or by country.

choropleth 2

Google has a nice way to do a simple choropleth map: Here is the code:

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<html><br/>
<head><br/>
<script type='text/javascript' src='https://www.google.com/jsapi'></script>
<script type='text/javascript'>
google.load('visualization', '1', {packages:['intensitymap']});       
google.setOnLoadCallback(drawChart);       
function drawChart() 
{         
var data = new google.visualization.DataTable();         
data.addColumn('string', '', 'State');         
data.addColumn('number', 'Accurate', 'a');         
data.addColumn('number', 'Ghost', 'b');         
data.addRows(6);         
data.setValue(0, 0, 'OH');         
data.setValue(0, 1, 1324);         
data.setValue(0, 2, 9640821);         
data.setValue(1, 0, 'IN');         
data.setValue(1, 1, 1133);         
data.setValue(1, 2, 3287263);         
data.setValue(2, 0, 'TN');         
data.setValue(2, 1, 304);         
data.setValue(2, 2, 9629091);         
data.setValue(3, 0, 'IO');         
data.setValue(3, 1, 232);         
data.setValue(3, 2, 1904569);         
data.setValue(4, 0, 'MA');         
data.setValue(4, 1, 187);         
data.setValue(4, 2, 8514877);  
data.setValue(5, 0, 'DC');         
data.setValue(5, 1, 187);         
data.setValue(5, 2, 8514877);        
var chart = new google.visualization.IntensityMap(document.getElementById('chart_div'));         
chart.draw(data, {region:'usa',width: 800, height: 640});       
} 
</script>
</head>
<body><br/>
<div id="chart_div"></div><br/>
</body>
</html>

Another method is to plug the address (& all data) into google fusion tables (here)

Google Map with marker size variation by frequency

Here are the easiest steps:

  1. You need a spreadsheet or CSV file with the following columns:
Description Latitude Longitude Frequency
Chicago 30.343 –44.43535 5
  1. If you need the lat and long data, but have the zipcode, name, address, or almost any scrap of data, go to this site. This can be a little tedious, but will give you the values. There are also lookup tables (xls) by zipcode. Perhaps a better option is this site, which allows you to simply paste in info such as :

Duke
Vanderbilt
University of Michigan

and get back latitude and longitude cooridinates.

  1. Take the above formatted csv file, and go to this very useful site. You can either upload or simply paste in the data and a google map is generated (or google earth map).