adding example

examples/node_features.py

@@ -0,0 +1,101 @@
+"""
+This example how request for each segmentation hypotheses features and use them
+to compute a custom edge weight between nodes, in this case, the cosine distance.
+
+For this we consider a 3D image as a 2D video, it's more a didactic example than a real use case.
+"""
+import napari
+import numpy as np
+from scipy.spatial.distance import cdist
+from skimage import morphology as morph
+from skimage.data import cells3d
+
+from ultrack import MainConfig, Tracker
+
+
+def main() -> None:
+
+    config = MainConfig()
+    config.data_config.working_dir = "/tmp/ultrack/."
+
+    # removing small segments
+    config.segmentation_config.min_area = 1_000
+    # disable division
+    config.tracking_config.division_weight = -1_000_000
+
+    tracker = Tracker(config)
+
+    # mocking a 3D image as 2D video
+    image = cells3d()[:, 1]  # nuclei
+
+    # simple foreground extraction
+    foreground = image > image.mean()
+    foreground = morph.opening(foreground, morph.disk(3)[None, :])
+    foreground = morph.closing(foreground, morph.disk(3)[None, :])
+
+    # contour as inverse of the image
+    contour = 1 - image / image.max()
+
+    tracker.segment(
+        foreground=foreground,
+        contours=contour,
+        image=image,
+        properties=["equivalent_diameter_area", "intensity_mean", "inertia_tensor"],
+        overwrite=True,
+    )
+
+    df = tracker.get_nodes_features()
+
+    # extending properties, some include -0-0, -0-1, -1-0, -1-1
+    cols = [
+        "y",
+        "x",
+        "area",
+        "intensity_mean",
+        "inertia_tensor-0-0",
+        "inertia_tensor-0-1",
+        "inertia_tensor-1-0",
+        "inertia_tensor-1-1",
+        "equivalent_diameter_area",
+    ]
+
+    # normalizing features
+    df[cols] -= df[cols].mean()
+    df[cols] /= df[cols].std()
+
+    df_by_t = df.groupby("t")
+    t_max = df["t"].max()
+
+    # iterating over time and querying pair of frames
+    for t in range(t_max + 1):
+        try:
+            # some frames might be without nodes
+            source_df = df_by_t.get_group(t)
+            target_df = df_by_t.get_group(t + 1)
+        except KeyError:
+            continue
+
+        # the higher the weights the more likely the link
+        weights = 1 - cdist(source_df[cols], target_df[cols], "cosine").ravel()
+
+        source_ids = np.repeat(source_df.index.to_numpy(), len(target_df))
+        target_ids = np.tile(target_df.index.to_numpy(), len(source_df))
+
+        # for very dense graph this not recommended because the ILP problem will be huge
+        tracker.add_links(sources=source_ids, targets=target_ids, weights=weights)
+
+    tracker.solve()
+
+    tracks, graph = tracker.to_tracks_layer()
+    segments = tracker.to_zarr()
+
+    viewer = napari.Viewer()
+    viewer.add_image(image, name="cells")
+    viewer.add_tracks(tracks[["track_id", "t", "y", "x"]], name="tracks", graph=graph)
+    viewer.add_labels(segments, name="segments")
+
+    napari.run()
+
+
+if __name__ == "__main__":
+    main()