Java Data Analysis

A spectacular example

In 1854, cholera broke out among the poor in London. The epidemic spread quickly, partly because nobody knew the source of the problem. But a physician named John Snow suspected it was caused by contaminated water. At that time, most Londoners drew their water from public wells that were supplied directly from the River Thames. The following figure shows the map that Snow drew, with black rectangles indicating the frequencies of cholera occurrences:

Figure 3 Dr. Snow's Cholera Map

If you look closely, you can also see the locations of nine public water pumps, marked as black dots and labeled PUMP. From this data, we can easily ...