Number of Acyclic Alkane Isomers - Python Version

 In the previous post I have outlined the method of calculating the number of open-chain alkane isomers in R. Since the calculation times for higher alkanes were impractically long, I have loosely translated, with minor changes, my program into python. The code follows below. As for the results - no substantial improvement could be observed. My next attempt would be in Java.

import networkx as nx

import matplotlib.pyplot as plt

import copy

from datetime import datetime

def addc(graph):

    n = graph.number_of_nodes()

    list = []

    for i in range(n):

        if graph.degree[i] < 4:        

            graph_c = copy.deepcopy(graph)

            graph_c.add_node(n)

            graph_c.add_edge(i, n)

            res = [nx.is_isomorphic(gr, graph_c) for gr in list]

            if not any(res):         

                list.append(graph_c)

    return list

def comblist(list1, list2):

    list_out = copy.deepcopy(list1)    

    for gr2 in list2:

        res = [nx.is_isomorphic(gr2,gr1) for gr1 in list1]

        if not any(res):

            list_out.append(gr2)            

    return list_out

def generate_isomers(depth):

    propane = nx.Graph()

    propane.add_nodes_from([0,1,2])

    propane.add_edge(0,1)

    propane.add_edge(1,2)

    iter_list = []

    iter_list.append(propane)    

    for a in range(4, depth+1): 

        total = []

        for grf in iter_list:

            new_list = addc(grf)

            if not total:

                total = total + new_list

            else:

                total =  comblist(total, new_list)

        nisomers = len(total)

        print(datetime.now())

        print(nisomers)

        iter_list = copy.deepcopy(total)

    return nisomers

To run it simply pass the desired number of carbons:

generate_isomers(10)

Glory to Ukraine! 
Слава Україні!