Implemented 3D connected components as wrapper class for scipy.ndimage.label

Ticket: https://www.notion.so/qim-dtu/3D-connected-components-ca5c410fef49444eac7c6efd0b56ead4?pvs=4

I have made a simple plot functions that takes the ConnectedComponents object and extracts the connected_components volume.

However I don't know if it is necessary as the user could do this manually.

def plot_connected_components(connected_components: ConnectedComponents, **kwargs):
    """ Plots connected components from the ConnectedComponents class as 2d slices.

    Args:
        connected_components (ConnectedComponents): The connected components class from the qim3d.utils.connected_components module.
        **kwargs: Additional keyword arguments to pass to qim3d.viz.img.slice_viz.

    Returns:
        matplotlib.pyplot: the 3D plot of the connected components.
    """
    fig = slice_viz(connected_components.connected_components, **kwargs)
    return fig

qim3d/utils/cc.py

@@ -30,7 +30,9 @@ class CC:
         Get the connected component with the given index, if index is None selects a random component.
 
         Args:
-            index (int): The index of the connected component. If none returns all components.
+            index (int): The index of the connected component. 
+                            If none returns all components.
+                            If 'random' returns a random component.
             crop (bool): If True, the volume is cropped to the bounding box of the connected component.
 
         Returns:
@@ -38,6 +40,9 @@ class CC:
         """
         if index is None:
             volume = self._connected_components
+        if index == "random":
+            index = np.random.randint(1, self.cc_count + 1)
+            volume = self._connected_components == index
         else:
             assert 1 <= index <= self.cc_count, "Index out of range. Needs to be in range [1, cc_count]."
             volume = self._connected_components == index