The code shown below computes an approximation algorithm, greedy heuristic, for the 0-1 knapsack problem in Apache Spark. Having worked with parallel dynamic programming algorithms a good amount, wanted to see what this would look like in Spark.
The Github code repo. for the
Knapsack approximation algorithms is here, and it includes a Scala solution. The work on a Java version is in progress at time of this writing.
Below we have the code that computes the solution that fits within the knapsack W for a set of items each with it's own weight and profit value. We look to maximize the final sum of selected items profits while not exceeding the total possible weight, W.
First we import some spark libraries into Python.
# Knapsack 0-1 function weights, values and size-capacity.
from pyspark.sql import SparkSession
from pyspark.sql.functions import lit
from pyspark.sql.functions import col
from pyspark.sql.functions import sum
Now define the function, which will take a Spark Dataframe w…