# Generating plane triangulations

Does sage have a function that generates plane triangulations? Something like PLANTRI? If not, is it possible to use plantri from within sage and how?

Thank you

Generating plane triangulations

Does sage have a function that generates plane triangulations? Something like PLANTRI? If not, is it possible to use plantri from within sage and how?

Thank you

add a comment

4

If you have plantri installed and somewhere in your PATH variable you can easily adapt the code of `graphs.nauty_geng`

to make it work with plantri. Something along the following lines might do the job:

```
def plantri(self, options=""):
import subprocess
sp = subprocess.Popen("plantri -g {0}".format(options), shell=True,
stdin=subprocess.PIPE, stdout=subprocess.PIPE,
stderr=subprocess.PIPE, close_fds=True)
gen = sp.stdout
while True:
try:
s = gen.next()
except StopIteration:
raise StopIteration("Exhausted list of graphs from plantri")
G = graph.Graph(s[:-1], format='graph6')
yield G
```

2

plantri is an optional package that you can install using

sage -i plantri

You will then be able to use the iterator over connected planar triangulations

```
sage: list(graphs.triangulations(6))
[Graph on 6 vertices, Graph on 6 vertices]
sage: all(g.is_planar() for g in graphs.triangulations(10))
True
```

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Asked: ** 2013-12-21 14:22:30 +0200 **

Seen: **543 times**

Last updated: **Mar 13 '19**

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