Identifying Gentrifiable Tracts

In this exercise, you will identify and map the tracts that were gentrifiable in 2000. The criteria are:

Low median household income (MHI), determined as tract MHI less than the MHI for the New York metro area.
A low level of recent housing construction, determined as those tracts with a percentage of housing built in the previous 20 years (since 1980) less than the percentage for the New York metro area.

The GeoDataFrame bk_2000, with data for Brooklyn Census tracts in 2000, has been loaded for you.

Calculate a boolean column low_mhi by checking to see whether mhi is less than mhi_msa
Calculate a boolean column low_recent_build by checking to see whether the percentage of homes built in the 20 years prior to 2000 (pct_recent_build) is less than pct_recent_build_msa
Use the & operator to classify the neighborhood as gentrifiable if both low_mhi and low_recent_build are true; the columns must be surrounded by parenthesis
Map the gentrifiable tracts using the YlGn colormap