Python Triangulation Reader

triangles.py

from typing import TextIO

# Problem: produce the dual graph for a triangulation

## This file contains the triangle parsing code.

example_triangulation = '''
VERTICES 4
0.000000 240.000000 0.000000
204.000000 240.000000 0.000000
240.000000 0.000000 0.000000
0.000000 0.000000 0.000000
TRIANGLES 2
0 1 3
1 2 3
'''.strip()


#  Notes: vertices is irrelevant, only triangles matter
def parse_triangulation(f: TextIO):
    """Return a reusable list of vertices and triangles.
    triangles[k] is a list of three numbers = the vertices for triangle k.

    Usage: 
        import io
        f = io.StringIO(example_triangulation)
          (v,t) = parse_triangulation(f) 
    or 
        with open("filename.txt") as f:
          (v,t) = parse_triangulation(f)

    Note - had to explicitly force map so the second iteration through the data would not get nothing. (BUGFIX)"""

    (_, nvertices) = f.readline().split()
    nvertices = int(nvertices)
    vertices = [list(map(float, f.readline().split())) for _ in range(nvertices)]

    (_, ntriangles) = f.readline().split()
    ntriangles = int(ntriangles)
    triangles = [list(map(int, f.readline().split())) for _ in range(ntriangles)]

    return (vertices, triangles)