# Import pandas 
import pandas as pd

# Load the customer_data
customer_data = pd.read_csv('customer_data.csv')

# Load the app_purchases
app_purchases = pd.read_csv('inapp_purchases.csv')

# Print the columns of customer data
print(customer_data.columns)

# Print the columns of app_purchases
print(app_purchases.columns)

# Merge on the 'uid' field
uid_combined_data = app_purchases.merge(customer_data, on=['uid'], how='inner')

# Examine the results 
print(uid_combined_data.head())
print(len(uid_combined_data))