sol.py

#+Title: Solution for In-Class Lab 2014-03-10 (COSC 251 SP14.6PM)
#+Author: Sean Allred and Molly Domino
#+Date: 2014-03-10
#+Objective: Read in a CSV, parse it as an adjacency matrix,
#+           and convert into an adjacency list.

# pretty-printing facilities
from pprint import pprint

print('Method 1: 21 lines of code (nothing fancy)')
lines = list()
try:                            # Read file
    f = open('graph.csv')
    lines = f.readlines()
    f.close()
except IOError:
    print("File doesn't exist?")

split_lines = list()            # Parse as matrix
for l in lines:
    split_lines.append(l.strip().split(','))

adj_list = dict()               # Parse into adjacency list
for row in range(len(split_lines)):
    for col in range(len(split_lines[row])):
        edge_char = split_lines[row][col].strip()
        if col > 0 and row is 0: # Header rows and columns
            adj_list[edge_char] = list()
        elif col > 0 and row > 0:
            col_char = split_lines[0][col]
            row_char = split_lines[row][0]
            if int(edge_char):       # if edge_char is '1', add to list
                adj_list[row_char].append(col_char.strip())

pprint(adj_list)

print('Method 2: 12 lines of code (lambdas, mapping, comprehensions, and slicing)')
matrix = None
try:
    with open('graph.csv') as f:
        # Read all lines in file, splitting them at commas
        matrix = [line.split(',') for line in f.readlines()]
except IOError: print("File doesn't exist?")

# Strip every element of every row in our matrix
matrix = [map(lambda s: s.strip(), row) for row in matrix]

# Construct an adjacency list from the very first row
adj_list2 = {node: list() for node in matrix[0][1:]}

# Iterate through
for row in matrix[1:]:
    col_idx = 1
    for el in row[1:]:
        # if this element is not zero, then append the appropriate
        # node to the list
        if int(el): adj_list2[row[0]].append(matrix[0][col_idx])
        col_idx += 1

pprint(adj_list2)

# Without comments, for comparison with Method 1

# matrix = None
# try:
#     with open('graph.csv') as f:
#         matrix = [line.split(',') for line in f.readlines()]
# except IOError: print("File doesn't exist?")
# matrix = [map(lambda s: s.strip(), row) for row in matrix]
# adj_list2 = {node: list() for node in matrix[0][1:]}
# for row in matrix[1:]:
#     col_idx = 1
#     for el in row[1:]:
#         if int(el): adj_list2[row[0]].append(matrix[0][col_idx])
#         col_idx += 1