DEAP: Genetic algorithm - eval function

Question

I am a beginner in Python and DEAP and I am trying to understand the evaluatiobn function for the TSP from: https://github.com/DEAP/deap/blob/master/examples/ga/tsp.py

def evalTSP(individual):
    distance = distance_map[individual[-1]][individual[0]]
    for gene1, gene2 in zip(individual[0:-1], individual[1:]):
        distance += distance_map[gene1][gene2]
    return distance,

On distance = distance_map[individual[-1]][individual[0]] The [individual[-1]][individual[0]] means the difference between the previous and the current individual positions?

On for gene1, gene2 in zip(individual[0:-1], individual[1:]) Which means the values 0:1 and 1: of individual?

This is actually two different questions that each already have an answer on site. — usernumber
– usernumber, Commented Nov 6, 2019 at 10:29

usernumber · Accepted Answer · 2019-11-06 10:28:30Z

1

Each individual is represented as an array. individual[-1] and individual[0] refer respectively to the last and the first gene of the individual (i.e element in the array). So distance_map[individual[-1]][individual[0]] is the distance between these two genes as stored in the DistanceMatrix.

individual[0:-1] returns an array with all the genes of individual except for the last one. individual[1:] returns an array with all the genes of individual except for the first one.

answered Nov 6, 2019 at 10:28

usernumber

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