DataCollector
def DataCollector(
fname_raster:str, # Path to the raster used as ground truth
band:int=1, # Band to read
):Emulate field measurements by reading a raster at sample locations.
Data Collector
Emulate a field campaign by reading measurements from a raster at sample locations.
DataCollector.get_values
def get_values(
gdf:geopandas.geodataframe.GeoDataFrame, # Sample locations as `Point` or `MultiPoint` geometries
)->list: # Raster value at each point, in the order of `gdf.get_coordinates()`Read the raster value of the cell under each point of gdf.
DataCollector.collect
def collect(
gdf:geopandas.geodataframe.GeoDataFrame, # Sample locations as `Point` or `MultiPoint` geometries, indexed by `loc_id`
)->geopandas.geodataframe.GeoDataFrame: # One `Point` per row with its measured `value`, indexed by `loc_id`Measure the raster at every point of gdf.
DataCollector stands in for a real field campaign. It treats a raster as the ground truth and reads the value under each sample location. Use it to test a sampling strategy before collecting real data. The example starts with a 10 by 10 grid over the raster:
fname_raster = './files/ground-truth-01-4326-simulated.tif'
gdf_grid = gridder(fname_raster, nrows=10, ncols=10)Draw between 1 and 9 points in each grid cell:
sampler = Sampler(gdf_grid)
n = np.random.default_rng(0).integers(1, 10, size=len(gdf_grid))
sample_locs = sampler.sample(n, method='uniform', rng=0)collect splits each MultiPoint into single points and reads the raster under each one. The result has one row per measurement. loc_id repeats for areas with several points:
dc_emulator = DataCollector(fname_raster)
samples_t0 = dc_emulator.collect(sample_locs)
test_eq(len(samples_t0), n.sum())
samples_t0.head()| geometry | value | |
|---|---|---|
| loc_id | ||
| 0 | POINT (-1.21382 43.26536) | 0.103400 |
| 0 | POINT (-1.2194 43.26891) | 0.137387 |
| 0 | POINT (-1.22288 43.26783) | 0.098744 |
| 0 | POINT (-1.21428 43.26705) | 0.110955 |
| 0 | POINT (-1.22325 43.26045) | 0.000000 |
ax = samples_t0.plot(column='value', s=3, legend=True)
gdf_grid.boundary.plot(color=black, lw=0.5, ax=ax)
ax.axis('off');