clip_data.py

"A module to clip vector data using geopandas"

# Create function to clip point data using geopandas


def clip_points(shp, clip_obj):
    '''
    Docs Here
    '''

    poly = clip_obj.geometry.unary_union
    return(shp[shp.geometry.intersects(poly)])

# Create function to clip line and polygon data using geopandas


def clip_line_poly(shp, clip_obj):
    '''
    docs
    '''

    # Create a single polygon object for clipping
    poly = clip_obj.geometry.unary_union
    spatial_index = shp.sindex

    # Create a box for the initial intersection
    bbox = poly.bounds
    # Get a list of id's for each road line that overlaps the bounding box and subset the data to just those lines
    sidx = list(spatial_index.intersection(bbox))
    #shp_sub = shp[shp.index.isin(sidx)]
    shp_sub = shp.iloc[sidx]

    # Clip the data - with these data
    clipped = shp_sub.copy()
    clipped['geometry'] = shp_sub.intersection(poly)

    # Return the clipped layer with no null geometry values
    return(clipped[clipped.geometry.notnull()])


# Final clip function that handles points, lines and polygons


def clip_shp(shp, clip_obj):
    '''
    '''
    if shp["geometry"].iloc[0].type == "Point":
        return(clip_points(shp, clip_obj))
    else:
        return(clip_line_poly(shp, clip_obj))