Question

Write some Python code that loads a textual file in DIMACS format into an internal represen- tation of a clause set, for which we will use a list of lists.

Answer 1

To load a DIMACS format file into a list of lists in Python, one should open the file, ignore comment and problem lines, and parse each clause into a sublist, excluding the terminating '0'. The function 'load_dimacs' demonstrates this process.

Step-by-step explanation:

Loading DIMACS Files in Python

To load a textual file in DIMACS format into an internal representation of a clause set using a list of lists in Python, you can follow this example code:

def load_dimacs(filename):
clause_set = []
with open(filename, 'r') as file:
for line in file:
if line.startswith('c') or line.startswith('p'):
continue
clause = [int(x) for x in line.strip().split() if x != '0']
clause_set.append(clause)
return clause_set

This function load_dimacs opens the specified file and reads it line by line. Lines beginning with 'c' are comments, and the line starting with 'p' contains the problem statement, both of which should be ignored. Each remaining line represents a clause, with integers separated by spaces. The function parses these integers into a list (ignoring the terminating '0'), and then appends this list to the clause_set, which is the final list of lists representation of the clauses.