Sage Interactions - Graph Theory

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TableOfContents

Automorphism Groups of some Graphs

by William Stein (I spent less than five minutes on this):

@interact
def _(graph=['CycleGraph', 'CubeGraph', 'RandomGNP'],
      n=selector([1..10],nrows=1), p=selector([10,20,..,100],nrows=1)):
    print graph
    if graph == 'CycleGraph':
       print "n (=%s): number of vertices"%n
       G = graphs.CycleGraph(n)
    elif graph == 'CubeGraph':
       if n > 8:
           print "n reduced to 8"
           n = 8
       print "n (=%s): dimension"%n
       G = graphs.CubeGraph(n)
    elif graph == 'RandomGNP':
       print "n (=%s) vertices"%n
       print "p (=%s%%) probability"%p
       G = graphs.RandomGNP(n, p/100.0)
    print G.automorphism_group()
    show(plot(G))

attachment:autograph.png

Graph Browser

by Marshall Hampton (Very simple so far.)

examples = {}
for g in grs:
    docs = eval('graphs.' + g + '.__doc__')
    for docline in docs.split('\n'):
        ex_loc = docline.find('graphs.' + g)
        if ex_loc != -1:
            end_paren_loc = docline[ex_loc:].find(')')
            ex_str = docline[ex_loc:end_paren_loc+ex_loc+1]
            ex_str = ex_str.replace('i+','2+')
            ex_str = ex_str.replace('(i','(4')
            break
    try:
        gt2 = eval(ex_str)
        examples[g] = ex_str
    except:
        grs.remove(g)
@interact
def graph_browser(graph_name = selector(grs, label = "Graph type:")):
    base_g_str = 'graphs.' + graph_name
    docs = eval(base_g_str + '.__doc__')
    doc_ex_loc = docs.find('EXAMPLE')
    if docs.find('PLOTTING') != -1:
        doc_ex_loc = min(doc_ex_loc, docs.find('PLOTTING'))
    print docs[0:doc_ex_loc].replace('\n        ','\n')
    t_graph = eval(examples[graph_name])
    show(t_graph)

attachment:graph_browse.png