examples/lsfiltration.py
 author Dmitriy Morozov Fri, 06 Nov 2009 14:19:08 -0800 branch dev changeset 173 5fd3f43e6fbf parent 142 ae2b1702c936 child 181 1ee6edc17cb6 permissions -rwxr-xr-x
```
#!/usr/bin/env python

from    dionysus        import Simplex, Filtration, StaticPersistence, vertex_cmp
from    sys             import argv, exit

def max_vertex(s, vertices):
return max((vertices[v] for v in s.vertices))

def max_vertex_cmp(s1, s2, vertices):
m1 = max_vertex(s1, vertices)
m2 = max_vertex(s2, vertices)
return cmp(m1, m2) or cmp(s1.dimension(), s2.dimension())

def lsf(values_filename, simplices_filename):
vertices = []
with open(values_filename) as f:
for line in f:
if line.startswith('#'): continue
vertices.append(float(line.split()))

simplices = []
with open(simplices_filename) as f:
for line in f:
if line.startswith('#'): continue
simplices.append(map(int, line.split()))

# Setup the complex
complex = [Simplex(s) for s in simplices]
complex.sort(vertex_cmp)

# Compute persistence
f = Filtration(complex, lambda x,y: max_vertex_cmp(x,y,vertices))
p = StaticPersistence(f)
p.pair_simplices()

# Output the persistence diagram
for i in p:
if not i.sign(): continue

b = complex[f[p(i)]]
d = complex[f[p(i.pair)]]

if i == i.pair:
print b.dimension(), max_vertex(b, vertices), "inf"
continue

print b.dimension(), max_vertex(b, vertices), max_vertex(d, vertices)

if __name__ == '__main__':
if len(argv) < 3:
print "Usage: %s VERTICES SIMPLICES" % argv
print
print "Computes persistence of the lower star filtration of the simplicial "
print "complex explicitly listed out in SIMPLICES with vertex values given in VERTICES."
exit()

values = argv
simplices = argv

lsf(values, simplices)
```