[PYSTOCK] DataFrame Column 선택 추가

from pandas import DataFrame

data = [[100,   0],
        [200,   0],
        [  0,  50],
        [  0, 300]]

df = DataFrame(data, columns=["col1", "col2"])
조건 = df["col1"] == 0

df["col3"] = 0
df.loc[ 조건, "col3"] = df["col2"]
df.loc[~조건, "col3"] = df["col1"]
print(df)