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July 23, 2020 22:22
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Playing with my son Federico
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| from collections import deque | |
| from subprocess import Popen, PIPE | |
| from sys import argv | |
| first, last = map(int, argv[1:3]) | |
| name = argv[3] | |
| ops = [ | |
| lambda x: x + 1, | |
| lambda x: x * 2 | |
| ] | |
| frontier = deque([first]) | |
| seen = set() | |
| graph = 'graph G {\nnode [shape=point]' | |
| while frontier: | |
| v = frontier.popleft() | |
| if v in seen: continue | |
| for op in ops: | |
| u = op(v) | |
| if u > last: continue | |
| graph += '\t{} -- {}'.format(v, u) | |
| frontier.append(u) | |
| seen.add(v) | |
| graph += '}' | |
| sfdp = Popen(['sfdp', '-Tpng'], stdin = PIPE, stdout = PIPE) | |
| with open('{}.png'.format(name), 'wb') as of: | |
| of.write(sfdp.communicate(input = graph)[0]) |
Just works on python 2.7. And here it produces really small images, like 179x173 with the args 1 10000. Any idea why?
I guess you mean 179x173 pixels, the image size depends on the sfdp tool, part of Graphviz. You can check the manual to see if you can specify a larger size, this Stack Overflow answer could be a good starting point.
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This is the script used to generate the above PNG, that also appears in this tweet; it is based on Graphviz and assumes
sfdplayout tool of such package to be in the path.The tool generates a graph G=(V, E) such that V = {
first<= x <=last} and E = {(x, y) : y = x + 1} U {(x, y) : y = 2x}To run it, just pass the
firstandlastnumber to consider and the basename of the graph, as inand open
graph.png.