calculate_features.py

'''Calculate features for the grid from other source data.

Chooses an appropriate calculator for the method given and creates new column(s)
in the grid table.

The following methods are available:

- cov: fraction of grid cell covered by given layer (optionally categorized by
  the value of a given field)
- dens: density of given layer features in grid cell (optionally categorized by
  the value of a given field)
- len: length of given layer features in grid cell (optionally categorized by
  the value of a given field)
- avg: average value of given field in grid cell
- wavg: average value of given field in grid cell, weighted by feature area
'''

import rum
import rum.calculate

argparser = rum.defaultArgumentParser(__doc__)
argparser.add_argument('table', help='calculation source table name')
argparser.add_argument('method', nargs='+', help='calculation method')
argparser.add_argument('-s', '--source-field', metavar='name', nargs='+',
    help='use this field from the source table in calculations')
argparser.add_argument('-c', '--case-field', metavar='name',
    help='perform the calculation separately for different values of this field')
argparser.add_argument('-o', '--overwrite', action='store_true',
    help='overwrite existing attributes'
)

if __name__ == '__main__':
    args = argparser.parse_args()
    rum.calculate.FeatureCalculator.fromArgs(args).run(
        args.table,
        args.method,
        sourceFields=args.source_field,
        caseField=args.case_field,
        overwrite=args.overwrite
    )