how to generate all 3 regular graphs given number of vertices in python

问题

I want to generate all 3-regular graphs with given number of vertices to check if some property applies to all of them or not. checking the property is easy but first I have to generate the graphs efficiently.

Can somebody please help me Generate these graphs (as adjacency matrix) or give me a file containing such graphs. Number of vertices are less than 24.

Thank you

回答1:

It is possible to read scd file into python as binary and convert data in same way it is done in readscd.c file. Here is an example:

import numpy

def convert(filename, n, k=3):
    num_edges = n*k/2
    f = open(filename, "r")
    values = numpy.fromfile(f, dtype=numpy.uint8)
    read_values = 0
    code = []
    while read_values < len(values):
        # dekomp(file,code)
        samebits = values.item(read_values)
        read_values += 1
        readbits = num_edges - samebits
        code = code[:samebits] + list(values[read_values:read_values+readbits])
        read_values += readbits
        # codetonlist(code,l)
        graph = numpy.zeros((n, n), dtype=numpy.uint8)
        v = 0
        count = [0] * n
        for w in code:
            w -= 1  # We are indexing from 0
            while(count[v] == k):
                v += 1
            # edge (v, w)
            graph.itemset((v, w), 1)
            graph.itemset((w, v), 1)
            count[v] += 1
            count[w] += 1
        yield graph

if __name__ == '__main__':
    import sys
    filename = sys.argv[1]
    nk = filename.split('.')[0].split('_')
    for g in convert(filename, int(nk[0]), int(nk[1])):
        print g

File 18_3_3.scd is processed in few seconds. Printing took few minutes.

来源：https://stackoverflow.com/questions/41355405/how-to-generate-all-3-regular-graphs-given-number-of-vertices-in-python