아미(아름다운미소)

import pandas as pdimport numpy as npimport time# 1. 예제 데이터 생성 (400만 건, '_' 없는 값 포함)data = {'a': ['foo_bar'] * 2_000_000 + ['hello_world'] * 1_500_000 + ['example'] * 500_000 + ['justtext'] * 500_000}df1 = pd.DataFrame(data) # Pandas용df2 = df1.copy() # NumPy용### 2. Pandas str.split(expand=True) 방식 ###start_time = time.time()debris = df1['a'].str.split('_', expand=True)df1['aaa'] = debris[0]df1..