Add script to compute grayscale image using PCA (#1299)

* Add script to compute grayscale image using PCA

* Fix isort

* Rename script

* Add scale parameter

experiments/ssl4eo/compute_dataset_pca.py

@@ -0,0 +1,30 @@
+#!/usr/bin/env python3
+
+import argparse
+import glob
+import os
+
+import numpy as np
+import rasterio as rio
+from sklearn.decomposition import IncrementalPCA
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument("directory", help="directory to recursively search for files")
+    parser.add_argument("--ext", default="tif", help="file extension")
+    parser.add_argument("--nan", default=0, type=float, help="fill value")
+    parser.add_argument("--scale", default=255, type=float, help="scale factor")
+    args = parser.parse_args()
+
+    transformer = IncrementalPCA(n_components=1)
+    for path in glob.iglob(
+        os.path.join(args.directory, "**", f"*.{args.ext}"), recursive=True
+    ):
+        with rio.open(path) as f:
+            x = f.read().astype(np.float32)
+            x /= args.scale
+            x = np.transpose(x, (1, 2, 0))
+            x = x.reshape((-1, x.shape[-1]))
+            transformer.partial_fit(x)
+
+    print("pca:", transformer.components_)