findSegments.py

# Solution for the SO question: http://stackoverflow.com/q/43702768/4045754
# 
# The files e.g. coordinates.txt are mentioned in the SO question

# Read data from the file
with open("coordinates.txt") as f:
    data = f.readlines()
data = [x.strip() for x in data]

# Final result
result = []

# Create a coordinate dictionary from the data
segDict = {}
for segment in data:
    coordinates = segment.split('), (')
    segDict[coordinates[0][2:]] = coordinates[1][:-2]


def getTupleFromStr(str):
    coordinates = str.split(',')
    return (int(coordinates[0]), int(coordinates[1]))

def getPolygon():
    start_coordinate = None
    poly = []
    
    # Get any key
    for key in segDict:
        start_coordinate = key
        poly.append('M')
        poly.append(getTupleFromStr(start_coordinate))
        poly.append('L')
        break

    while key in segDict:
        newKey = segDict[key]
        del(segDict[key])
        poly.append(getTupleFromStr(newKey))
        key = newKey

    #Push to result if polygon complete
    if key == start_coordinate:
        result.extend(poly[:-1]) #exclude the last coordinate as it is same as first one

# Discover polygons from the segDict
while len(segDict) > 0:
    getPolygon()

print result