"""
Code copied from pages 188-189 of the Mastering SciPy book of
Francisco J. Blanco-Silva, Packt Publishing 2015.
"""
def read_poly(file_name):
    """
    Simple poly-file reader, that creates a python dictionary
    with information about vertices, edges and holes.
    It assumes that vertices have no attributes or boundary markers.
    It assumes that edges have no boundary markers.
    No regional attributes or area constraints are parsed.
    """
    from numpy import array
    output = {'vertices': None, 'holes': None, 'segments': None}
    # open file and store lines in a list
    file = open(file_name, 'r')
    lines = file.readlines()
    file.close()
    lines = [x.strip('\n').split() for x in lines]
    # Store vertices
    vertices= []
    N_vertices,dimension,attr,bdry_markers = [int(x) for x in lines[0]]
    # We assume attr = bdrt_markers = 0
    for k in range(N_vertices):
        label,x,y = [items for items in lines[k+1]]
        vertices.append([float(x), float(y)])
    output['vertices'] = array(vertices)
    # Store segments
    segments = []
    N_segments,bdry_markers = [int(x) for x in lines[N_vertices+1]]
    for k in range(N_segments):
        label,pointer_1,pointer_2 = [items for items in lines[N_vertices+k+2]]
        segments.append([int(pointer_1)-1, int(pointer_2)-1])
    output['segments'] = array(segments)
    # Store holes
    N_holes = int(lines[N_segments+N_vertices+2][0])
    holes = []
    for k in range(N_holes):
        label,x,y = [items for items in lines[N_segments + N_vertices + 3 + k]]
        holes.append([float(x), float(y)])
    output['holes'] = array(holes)
    return output