基于Python Pandas其他列条件新增交易分类列的实现需求

Got it, let's tackle this problem step by step. The goal is to categorize each transaction based on whether it contains only category X, only category Y, or a mix of both. Here's a straightforward solution:

Full Working Code #

import pandas as pd

# Initialize your DataFrame as provided
df = pd.DataFrame({
    'transaction_id': ['A123','A123','B345','B345','C567','C567','D678','D678'], 
    'product_id': [255472, 251235, 253764,257344,221577,209809,223551,290678], 
    'product_category': ['X','X','Y','Y','X','Y','Y','X']
})

# Define a helper function to categorize each transaction
def categorize_transaction(categories):
    unique_cats = set(categories)
    if unique_cats == {'X'}:
        return 'Only X'
    elif unique_cats == {'Y'}:
        return 'Only Y'
    else:
        return 'Mixed X&Y'

# Apply the function to each transaction group and merge back to the original DataFrame
df['transaction_category'] = df.groupby('transaction_id')['product_category'].transform(categorize_transaction)

# Print the result to verify
print(df)

How It Works #

1. Helper Function: The categorize_transaction function takes all product categories for a single transaction, converts them to a set (to get unique values), and returns the appropriate category label.
2. Group & Transform: Using groupby('transaction_id') groups rows by each unique transaction ID. The transform method ensures we keep the original row count—instead of returning a condensed group result, it maps the category label back to every row in the original transaction.
3. Assign New Column: The result of the transform is directly assigned to the new transaction_category column.

Result #

After running the code, your DataFrame will look like this:

Alternative Concise Version #

If you prefer a one-liner without a separate helper function, you can use a lambda directly in the transform:

df['transaction_category'] = df.groupby('transaction_id')['product_category'].transform(
    lambda x: 'Only X' if set(x) == {'X'} else ('Only Y' if set(x) == {'Y'} else 'Mixed X&Y')
)

内容的提问来源于stack exchange，提问作者jeangelj