A Function I Am Proud Of

firebird.py

@entrypoint.command()
@click.option('--x',        '-x', required=True)
@click.option('--y',        '-y', required=True)
@click.option('--acquired', '-a', required=True)
@click.option('--number',   '-n', required=False, default=2500)
def changedetection(x, y, acquired, number=2500):
    """Run change detection for a tile over a time range and save results to Cassandra.
    
    Args:
        x        (int): tile x coordinate
        y        (int): tile y coordinate
        acquired (str): ISO8601 date range
        number   (int): Number of chips to run change detection on.  Testing only.

    Returns:
        count of saved segments 
    """

    
    ctx  = None
    name = 'change-detection'
    
    try:
        # start and/or connect Spark
        ctx = firebird.context(name)

        # get logger
        log = logger(ctx, name)
        
        # wire everything up
        tile = grids.tile(x=x, y=y, cfg=ARD)
        ids  = timeseries.ids(ctx=ctx, chips=take(number, tile.get('chips')))
        ard  = timeseries.rdd(ctx=ctx, ids=ids, acquired=acquired, cfg=firebird.ARD, name='ard')
        ccd  = pyccd.dataframe(ctx=ctx, rdd=pyccd.rdd(ctx=ctx, timeseries=ard)).cache()

        # emit parameters
        log.info(str(merge(tile, {'acquired': acquired,
                                  'input-partitions': firebird.INPUT_PARTITIONS,
                                  'product-partitions': firebird.PRODUCT_PARTITIONS,
                                  'chips': ids.count()})))

        # realize data transformations
        cassandra.write(ctx, ccd, cqlstr(pyccd.algorithm()))

        # log and return segment counts
        return do(log.info "saved {} ccd segments".format(get('ccd', counts)))
            
    except Exception as e:
        # spark errors & stack trace
        print('error:{}'.format(e))
        traceback.print_exc()
        
    finally:
        # stop and/or disconnect Spark
        if ctx is not None:
            ctx.stop()
            ctx = None