1) Three clusters:

Cluster 0: Upper manhattan, Lower east Manhattan, most of Bronx and part of Brooklyn (near Queens)

Cluster 1: Downtown, Midtown and Uptown manhattan, part of Brooklyn (near downtown manhattan)

Cluster 2: Staten island, north and east end of Bronx and part of Brooklyn (near Staten island)

2) Taxi services and tipping behavior in three clusters:

Taxi services:

Cluster 0: 1000 trips per hour on average; Most dense taxi time is midnight and early morning at weekends.

Cluster 1: 10000 trips per hour on average; Most dense taxi time is midnight at weekends, 8-9am and 9-8pm at workdays.

Cluster 2: 4 trips per hour on average; Most dense taxi time is midnight at weekends, 7-8am at workdays.

Tipping behavior:

Generally, people in Cluster 2, rarely taking taxi though, tip more on average;

People in Cluster 1 show the most stable tipping behavior, almost all of them tip roughly at 20%;

People in Cluster 0 tip very differently, from 12% to 21%.

Quadratic relation between average tip percentage and median household income those most rich people didn't tip more.

Quadratic relation between average tip percentage and public transportation rate those people who rarely taking public transportation to work tend to tip more.

Linear relation between average tip percentage and white rate average tip percentage is 16% in those area with rare white people; but higher to 20% where most people are white.