def truncated_simplex_tree(simplexTree: np.ndarray,
int_trunc: int = 100) -> tuple:
"""
**This function return a truncated simplex tree.**
A sparse representation of the persistence diagram in the form of a truncated
persistence tree. Speeds up computation on large scale data sets.
+ param **simplexTree**: simplex tree, type `np.ndarray`.
+ param **int_trunc**: number of persistent interval kept per dimension, default is `100`, type `int`.
+ return **simplexTreeTruncatedPersistence**: truncated simplex tree, type `np.ndarray`.
"""
simplexTree.persistence()
dimension = simplexTree.dimension()
simplexTreeTruncatedPersistence = []
for i in range(dimension):
dPersistence = simplexTree.persistence_intervals_in_dimension(
dimension)
j = len(dPersistence)
if j > int_trunc:
dPersistenceTruncated = [
dPersistence[i] for i in range(j - int_trunc, j)
]
else:
dPersistenceTruncated = dPersistence
simplexTreeTruncatedPersistence = simplexTreeTruncatedPersistence + [
(i, (l[0], l[1])) for l in dPersistenceTruncated
]
return simplexTreeTruncatedPersistence