Filtering Data

Spatial Filters

nvcl-kit allows you to filter boreholes based on a polygon geometry. This is particularly useful when you want to focus on a specific area of interest. You can use any polygon geometry, such as a shapefile, geojson, or even a manually created polygon using the Shapely library.

Start by loading your Shapefile using the geopandas.read_file() method. The shapefile should contain a polygon geometry that will be used to filter the boreholes.

import geopandas as gpd

# Load the shapefile. This could also be a geojson file or any other format supported by Geopandas
gdf = gpd.read_file("polygon.shp")

# Check the coordinate reference system (CRS) of the shapefile
print(gdf.crs)

Next, import the necessary modules and initialise the NVCLReader. You can pass the polygon geometry as a parameter to param_builder(). The reader will then use this polygon to filter the boreholes and only return those that exist within the polygon. The polygon parameter supports both shapely.Polygon and shapely.MultiPolygon geometries.

# Import the necessary modules
import pandas as pd
from nvcl_kit.generators import gen_summary_dataframe
from nvcl_kit.param_builder import param_builder
from nvcl_kit.reader import NVCLReader

# Initialise NVCL reader and filter using the first geometry in the GeoDataFrame
param = param_builder("NSW", polygon=gdf.geometry[0])
reader = NVCLReader(param)
if not reader.wfs:
    print("Error: Cannot contact service")

By default the reader will assume that a polygon is provided in EPSG:4326. If your polygon uses a different Coordinate Reference System (CRS), make sure to specify the correct SRID using polygon_srid when building the parameters.

# Initialise NVCL reader with polygon in a different CRS (e.g., EPSG:3857)
param = param_builder("NSW", polygon=gdf.geometry[0], polygon_srid=3857)
reader = NVCLReader(param)
if not reader.wfs:
    print("Error: Cannot contact service")

If your polygon contains interior rings (holes), you can ask nvcl-kit to remove them by setting the remove_rings parameter to True when building the parameters. This will ensure that the filter only considers the exterior boundary of the polygon(s).

# Initialise NVCL reader with option to remove interior rings from the polygon
param = param_builder("NSW", polygon=gdf.geometry[0], polygon_srid=gdf.crs.to_epsg(), remove_rings=True)
reader = NVCLReader(param)
if not reader.wfs:
    print("Error: Cannot contact service")

MultiPolygon with interior rings removed prior to filtering.

MultiPolygon with interior rings (holes).