Python 3: How to remove the odd ones in a python list

Question

Below is the example for reference:

pairlist = [("A","B"),("Q","R"),("S","T"),("C","E"),("F","G"),("G","I"),("A","Y"),("B","C"),("B","D")]

I need to get the more interconnected values (directly or Indirectly) of tuples from this list

for Example: Refer below list where "A" is linked with "B" in tuple("A","B") in the pairlist[0] position, and "B" is linked with "C" in pairlist[7] and so on it is interconnected indirectly in large number, where as "G" is less interconnected.

pairs1 = ["A", "B", "C", "D", "E", "Y"] #More Interconnected indirectly

pairs2 = ["G", "F", "I"] #Less Interconnected indirectly

The below tuples in the list No where Interconnected with any one.

("Q","R"),("S","T")

Even though "G" is repetitive and it is not interconnected with major once, it seperately interconnected with other elements which is very less connections with others.

How to get the list as below

pairs = ["A", "B", "C", "D", "E", "Y"]

You are looking for the _largest connected component_ in a graph. Try a web search with that term and you should be able to find something. — Ray Toal, Feb 03 '19 at 08:51
Possible duplicate of [Python connected components](https://stackoverflow.com/questions/10301000/python-connected-components) — Mykola Zotko, Feb 03 '19 at 09:16
Edited with more details, could you pls refer again and share the solution — Manjunathan Venkatesan, Feb 03 '19 at 09:48

Mykola Zotko · Accepted Answer · 2019-02-03T10:09:19.030

3

You can use the package networkx:

import networkx as nx

pairlist = [("A","B"),("C","E"),("F","G"),("G","I"),("A","Y"),("B","C"),("B","D")]

G = nx.Graph()
G.add_edges_from(pairlist)
for i in nx.connected_components(G):
    print(i)
# {'B', 'C', 'E', 'D', 'Y', 'A'}
# {'I', 'F', 'G'}

To draw the graph use:

import matplotlib.pyplot as plt

nx.draw(G, with_labels=True)
plt.show()

or if you use jupyter notebook:

%matplotlib inline
nx.draw(G, with_labels=True)

edited Feb 03 '19 at 10:09

answered Feb 03 '19 at 09:05

Mykola Zotko

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Thanks a lot for your solution...Amazing work out, you have Done great job – Manjunathan Venkatesan Feb 03 '19 at 09:52
How to get graph or plot? – Manjunathan Venkatesan Feb 03 '19 at 09:53
@ManjunathanVenkatesan I‘ve added infos how to draw the graph to my answer. – Mykola Zotko Feb 03 '19 at 10:11

Python 3: How to remove the odd ones in a python list

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