資料集來源：https://www.kaggle.com/psparks/instacart-market-basket-analysis

思路：

例項程式碼：

import pandas as pd
from sklearn.decomposition import PCA

def main():
    '''
    降維例項：主成分分析
    :return: None
    '''
    # 讀取資料
    prior = pd.read_csv("order_products__prior.csv")
    products 
 
= pd.read_csv("products.csv")
    orders = pd.read_csv("orders.csv")
    aisles = pd.read_csv("aisles.csv")
    # 合併資料
    _mg = pd.merge(prior, products, on=['product_id', 'product_id'])
    _mg = pd.merge(_mg, orders, on=['order_id', 'order_id'])
    mt = pd.merge(_mg, aisles, on=['aisle_id'
 
, 'aisle_id'])
    # print(mt.head(10))
    # 交叉表
    cross = pd.crosstab(mt['user_id'], mt['aisle'])
    # print(cross)
    pca = PCA(n_components=0.9)
    data = pca.fit_transform(cross)
    print(data)
    print(data.shape)
    return None

if __name__ == '__main__':
    main()

執行結果：

從結果中可以看出資料的維數降到了27