From d7677b1f3f5ceee9cfdb5275ef00cbf79a714122 Mon Sep 17 00:00:00 2001
From: Bryn Keller <xoltar@xoltar.org>
Date: Mon, 7 Mar 2016 13:51:48 -0800
Subject: Python interface to PHAT

---
 python/src/simple_example.py | 59 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)
 create mode 100644 python/src/simple_example.py

(limited to 'python/src/simple_example.py')

diff --git a/python/src/simple_example.py b/python/src/simple_example.py
new file mode 100644
index 0000000..82cf6be
--- /dev/null
+++ b/python/src/simple_example.py
@@ -0,0 +1,59 @@
+"""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
+
+    # set the dimension of the cell that each column represents:
+    dimensions = [0, 0, 1, 0, 1, 1, 2]
+
+    # define a boundary matrix with the chosen internal representation
+    boundary_matrix = phat.boundary_matrix(representation = phat.representations.vector_vector)
+
+    # set the respective columns -- the columns entries have to be sorted
+    boundary_matrix.set_dims(dimensions)
+    boundary_matrix.set_col(0, [])
+    boundary_matrix.set_col(1, [])
+    boundary_matrix.set_col(2, [0,1])
+    boundary_matrix.set_col(3, [])
+    boundary_matrix.set_col(4, [1,3])
+    boundary_matrix.set_col(5, [0,3])
+    boundary_matrix.set_col(6, [2,4,5])
+
+    # print some information of the boundary matrix:
+    print()
+    print("The boundary matrix has %d columns:" % boundary_matrix.get_num_cols())
+    for col_idx in range(boundary_matrix.get_num_cols()):
+        s = "Column %d represents a cell of dimension %d." % (col_idx, boundary_matrix.get_dim(col_idx))
+        if (not boundary_matrix.is_empty(col_idx)):
+            s = s + " Its boundary consists of the cells " + " ".join([str(c) for c in boundary_matrix.get_col(col_idx)])
+        print(s)
+    print("Overall, the boundary matrix has %d entries." % boundary_matrix.get_num_entries())
+
+    pairs = phat.compute_persistence_pairs(boundary_matrix)
+
+    pairs.sort()
+
+    print()
+
+    print("There are %d persistence pairs: " % len(pairs))
+    for pair in pairs:
+        print("Birth: %d, Death: %d" % pair)
+
-- 
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