Merge pull request #68 from earth-chris/sample-raster-nodata

assign nodata in sample_raster

elapid/__version__.py

@@ -1 +1 @@
-"0.3.15"
+"0.3.16"

elapid/geo.py

@@ -98,14 +98,15 @@ def stack_geometries(
  return gdf
 
 
-def sample_raster(raster_path: str, count: int, ignore_mask: bool = False) -> gpd.GeoSeries:
- """Creates a random geographic sampling of points based on a raster's extent.
+def sample_raster(raster_path: str, count: int, nodata: float = None, ignore_mask: bool = False) -> gpd.GeoSeries:
+ """Create a random geographic sample of points based on a raster's extent.
 
  Selects from unmasked locations if the rasters nodata value is set.
 
  Args:
  raster_path: raster file path to sample locations from
  count: number of samples to generate
+ nodata: add pixels with this value to the nodata mask
  ignore_mask: sample from the full extent of the raster instead of unmasked areas only
 
  Returns:
@@ -119,8 +120,14 @@ def sample_raster(raster_path: str, count: int, ignore_mask: bool = False) -> gp
  xy = np.random.uniform((xmin, ymin), (xmax, ymax), (count, 2))
 
  else:
- masked = src.read_masks(1)
- rows, cols = np.where(masked == 255)
+ if nodata is None:
+ masked = src.read_masks(1)
+ rows, cols = np.where(masked == 255)
+ else:
+ data = src.read(1, masked=True)
+ data.mask += data.data == nodata
+ rows, cols = np.where(~data.mask)
+
  samples = np.random.randint(0, len(rows), count)
  xy = np.zeros((count, 2))
  for i, sample in enumerate(samples):