Function:
cropregion crops the data in the nc file as per the bounding
box provided as the fourth argument
Syntax:
[lon_cropped, lat_cropped, data_cropped]=cropregion(lon,lat,data,[lon1 lon2 lat1 lat2]);

Inputs:
It takes the first three arguments as the latitude, longitude, and
data respectively. The fourth argument should be the bounding box of the region(s) you wish to crop.

Example:

W=shaperead('us_states.shp');
[xx,yy,zz]=cropregion(lon,lat,data,[-79.5683 -74.7735 33.5789 36.7302])