조건 선택과 query

# 단일 조건
mask = df["age"] >= 30
out1 = df.loc[mask]

# 복합 조건
mask2 = (df["age"] >= 30) & (df["amount"] >= 10000)
out2 = df.loc[mask2, ["name", "amount"]]

# isin / between
out3 = df.loc[df["region"].isin(["seoul", "busan"])]
out4 = df.loc[df["amount"].between(8000, 15000)]

threshold = 10000
regions = ["seoul", "busan"]

q = df.query("age >= 30 and amount >= @threshold and region in @regions")

name_mask = df["name"].str.contains("kim|lee", regex=True, na=False)
out = df.loc[name_mask]