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+"""This file contains a simple example that demonstrates the usage of the library interface"""
+
+if __name__ == "__main__":
+
+ print("""
+ we will build an ordered boundary matrix of this simplicial complex consisting of a single triangle:
+
+ 3
+ |\\
+ | \\
+ | \\
+ | \\ 4
+ 5| \\
+ | \\
+ | 6 \\
+ | \\
+ |________\\
+ 0 2 1
+
+""")
+
+ import phat
+
+ # define a boundary matrix with the chosen internal representation
+ boundary_matrix = phat.boundary_matrix(representation = phat.representations.vector_vector)
+
+ # set the respective columns -- (dimension, boundary) pairs
+ boundary_matrix.columns = [ (0, []),
+ (0, []),
+ (1, [0,1]),
+ (0, []),
+ (1, [1,3]),
+ (1, [0,3]),
+ (2, [2,4,5])]
+
+ # or equivalently, boundary_matrix = phat.boundary_matrix(representation = ..., columns = ...)
+ # would combine the creation of the matrix and the assignment of the columns
+
+ # print some information of the boundary matrix:
+ print("\nThe boundary matrix has %d columns:" % len(boundary_matrix.columns))
+ for col in boundary_matrix.columns:
+ s = "Column %d represents a cell of dimension %d." % (col.index, col.dimension)
+ if (col.boundary):
+ s = s + " Its boundary consists of the cells " + " ".join([str(c) for c in col.boundary])
+ print(s)
+ print("Overall, the boundary matrix has %d entries." % len(boundary_matrix))
+
+ pairs = boundary_matrix.compute_persistence_pairs()
+
+ pairs.sort()
+
+ print("\nThere are %d persistence pairs: " % len(pairs))
+ for pair in pairs:
+ print("Birth: %d, Death: %d" % pair)
+