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#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Tests for algorithms related to association rules.
"""
import pytest
import itertools
import random
from efficient_apriori.itemsets import itemsets_from_transactions, ItemsetCount
def generate_transactions(num_transactions, unique_items, items_row=(1, 100), seed=None):
"""
Generate synthetic transactions.
"""
if seed:
random.seed(seed)
else:
random.seed()
items = list(range(unique_items))
for _ in range(num_transactions):
items_this_row = random.randint(*items_row)
yield random.sample(items, k=min(unique_items, items_this_row))
def itemsets_from_transactions_naive(transactions, min_support):
"""
Naive algorithm used for testing only.
"""
# Get the unique items from every transaction
unique_items = {k for ts in transactions for k in ts}
num_transactions = len(transactions)
# Create an output dictionary
L = dict()
# For every possible combination length
for k in range(1, len(unique_items) + 1):
# For every possible combination
for combination in itertools.combinations(unique_items, k):
# Naively count how many transactions contain the combination
counts = ItemsetCount()
for i, t in enumerate(transactions):
if set.issubset(set(combination), set(t)):
counts.itemset_count += 1
counts.members.add(i)
# If the count exceeds the minimum support, add it
if (counts.itemset_count / num_transactions) >= min_support:
try:
L[k][tuple(sorted(list(combination)))] = counts
except KeyError:
L[k] = dict()
L[k][tuple(sorted(list(combination)))] = counts
try:
L[k] = {k: v for (k, v) in sorted(L[k].items())}
if L[k] == {}:
del L[k]
return L, num_transactions
except KeyError:
return L, num_transactions
return L, num_transactions
input_data = [
(
list(
generate_transactions(
random.randint(5, 25),
random.randint(1, 8),
(1, random.randint(2, 8)),
)
),
random.randint(1, 4) / 10,
)
for i in range(500)
]
@pytest.mark.parametrize("transactions, min_support", input_data)
def test_itemsets_from_transactions_stochastic(transactions, min_support):
"""
Test random inputs.
"""
result, _ = itemsets_from_transactions(list(transactions), min_support, output_transaction_ids=True)
naive_result, _ = itemsets_from_transactions_naive(list(transactions), min_support)
for key in set.union(set(result.keys()), set(naive_result.keys())):
assert result[key] == naive_result[key]
@pytest.mark.parametrize("transactions, min_support", input_data)
def test_itemsets_max_length(transactions, min_support):
"""
The that nothing larger than max length is returned.
"""
max_len = random.randint(1, 5)
result, _ = itemsets_from_transactions(
list(transactions),
min_support,
max_length=max_len,
output_transaction_ids=True,
)
assert all(list(k <= max_len for k in result.keys()))
for length, itemsets in result.items():
for itemset_count in itemsets.values():
assert all(isinstance(i, int) for i in itemset_count.members)
if __name__ == "__main__":
pytest.main(args=[".", "--doctest-modules", "-v"])
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