Hacking Google Maps and Google Earth (ExtremeTech)

182 Part III — Google Map Hacks

The U.S. Census Data

For the examples in this chapter the population of different cities in the U.S. is used to provide

the statistical information that is displayed on the map. The information used comes from the

U.S. Census data and is based on questionnaires completed by the public. Looking at a table of

that information (Table 10-1) is not a clear way to view the data. The table has been deliber-

ately sorted alphabetically so there isn’t any order to the population statistics.

Table 10-1 U.S. Census City Population Data

City 2004 2000 1990

Chicago, Ill. 2,862,244 2,896,016 2,783,726

Columbus, Ohio 730,008 711,470 632,910

Dallas, Tex. 1,210,393 1,188,580 1,006,877

Detroit, Mich. 900,198 951,270 1,027,974

Houston, Tex. 2,012,626 1,953,631 1,630,553

Indianapolis, Ind. 784,242 781,870 741,952

Jacksonville, Fla. 777,704 735,617 635,230

Los Angeles, Calif. 3,845,541 3,694,820 3,485,398

New York, N.Y. 8,104,079 8,008,278 7,322,564

Philadelphia, Pa. 1,470,151 1,517,550 1,585,577

Phoenix, Ariz. 1,418,041 1,321,045 983,403

San Antonio, Tex. 1,236,249 1,144,646 935,933

San Diego, Calif. 1,263,756 1,223,400 1,110,549

San Francisco, Calif. 744,230 776,733 723,959

San Jose, Calif. 904,522 894,943 782,248

With a little work it is possible to pull out key points, such as the number of people living in

New York is obviously quite high, but making comparisons can be quite difficult.

Two columns were added to the table: the latitude and longitude of each city shown.

Otherwise, the data used is exactly as shown here.

Converting the Source Data to XML

The preceding table was saved as a tab-delimited text file and then processed through the

following simple script. The script is designed to handle as many years (identified by extracting

the years from the “header” row in the text file), even though the data used throughout this

chapter consists of just the three years shown, 1990, 2000, and 2004.