Challenge: Apriori Algorithm Implementation

Now we will implement Apriori algorithm using mlxtend library.
Let's discover some implementation key points:

We will utilize the mlxtend.frequent_patterns module to detect frequent itemsets using the Apriori algorithm and to provide association rules;
The Apriori algorithm is implemented using the apriori(data, min_support, use_colnames=True) function. Note that the data argument represents the transaction dataset in one-hot-encoded format. The min_support argument is a numerical value that represents the minimum support threshold;
To detect association rules, we can use the association_rules(frequent_itemsets, metric, min_threshold) function. The frequent_itemsets variable represents a list of frequent itemsets generated by the apriori function, and the metric variable represents the metric name in a string format that we use to measure the strength of the association rule. The min_threshold argument represents the minimum threshold value of the metric to detect significant association rules.

What is one-hot-encoded format

One-hot encoding is a technique used to convert categorical variables into a numerical format that can be used for machine learning algorithms. It involves representing each category in a categorical variable as a binary vector, where each vector has a length equal to the number of unique categories in the variable. The vector is all zeros except for the index corresponding to the category, which is set to 1.

Suppose we have the following transaction dataset for Apriori algorithm:

We want to convert the "Items" column into a one-hot encoded format.

After One-Hot Encoding:

Tarea

Swipe to start coding

Your task is to find frequent itemsets and association rules in the given dataset. You need to use the apriori() function with one-hot-encoded data and a minimum support value of 0.2 as arguments to detect frequent itemsets. Then, use the association_rules() function with the frequent itemsets, confidence, and minimum threshold value of 0.7 as arguments to detect association rules.

Solución

from mlxtend.frequent_patterns import apriori

from mlxtend.frequent_patterns import association_rules

import pandas as pd

from mlxtend.preprocessing import TransactionEncoder

# Example transaction dataset

dataset = [

["milk", "bread", "eggs", "cheese", "yogurt"],

["bread", "butter", "jam", "eggs", "cheese"],

["milk", "bread", "butter", "jam", "yogurt"],

["milk", "eggs", "cheese", "yogurt", "fruit"],

["bread", "eggs", "butter", "jam", "honey"],

["bread", "eggs", "jam", "yogurt", "fruit"],

["bread", "milk", "eggs", "butter", "jam", "cheese", "yogurt"],

["milk", "cheese", "jam", "honey", "fruit"],

["bread", "milk", "eggs", "butter", "jam", "honey"]

]

# Convert the dataset into a DataFrame

df = pd.DataFrame(dataset)

# Apply transaction encoding

encoder = TransactionEncoder()

encoded_transactions = encoder.fit_transform(dataset)

# Convert encoded transactions to DataFrame

df_encoded = pd.DataFrame(encoded_transactions, columns=encoder.columns_)

# Find frequent itemsets using the Apriori algorithm

frequent_itemsets = apriori(df_encoded, min_support=0.2, use_colnames=True)

# Print frequent itemsets

print("Frequent Itemsets:")

print(frequent_itemsets)

# Generate association rules

¿Todo estuvo claro?

¡Gracias por tus comentarios!

Sección 2. Capítulo 2

# Import necessary functions from the `mlxtend` library