Find rows which share common elements

Question

I have a 2D numpy array in which each row contains 2 integers. I want to find all the groups of elements belonging to rows which share common elements (a.k.a connected components of a graph from the edgelist array). For example, for the array:

[[ 0  4]
 [ 0  7]
 [ 1  2]
 [ 1 13]
 [ 2  1]
 [ 2  9]
 [ 3 14]
 [ 3 16]
 [ 4  0]
 [ 4  5]
 [ 5  4]
 [ 5  6]
 [ 6  5]
 [ 6  7]
 [ 7  0]
 [ 7  6]]

would contain the groups

[[ 0  4  5  6  7]
 [ 1  2 13  9]
 [ 3 14 16]]

Answer 1

If you can use libraries, assuming your array is a (Note that you cannot have components as numpy array since they can be non-rectangular array which does not exist in numpy, so this outputs them as sets):

import networkx as nx
G=nx.Graph()
G.add_edges_from(a)
print(sorted(nx.connected_components(G), key = len, reverse=True))
#[{0, 4, 5, 6, 7}, {1, 2, 13, 9}, {16, 3, 14}]

And if you need a pure numpyic solution without extra libraries, please check out this generalized solution: https://stackoverflow.com/a/61764414/4975981