请教如何根据条件使用 numpy 函数生成一个新的数组 - V2EX
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songdg
V2EX    Python

请教如何根据条件使用 numpy 函数生成一个新的数组

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  •   songdg 2023-02-15 16:50:20 +08:00 1863 次点击
    这是一个创建于 1000 天前的主题,其中的信息可能已经有所发展或是发生改变。

    请教如何通过数组 A 、B 得到 C ,先判断 B 中是否有重复,然后在 A 中找最大的其余的设为 0 。 A = array([3.33, 1.18, 5.42, 4.12])、B = array([449, 3676, 10975, 10975])、C = array([3.33, 1.18, 5.42, 0])

    3 条回复    2023-02-18 14:52:32 +08:00
    TimePPT
        1
    TimePPT  
    PRO
       2023-02-15 17:38:03 +08:00   1
    import pandas as pd
    import numpy as np

    A = np.array([3.33, 1.18, 5.42, 4.12])
    B = np.array([449, 3676, 10975, 10975])
    df = pd.DataFrame(data={"A": A, "B": B})
    df["C"] = df.groupby("B")["A"].transform("max")
    df["C"] = df.apply(lambda row: 0 if row["C"] > row["A"] else row["C"], axis=1)
    df
    TimePPT
        2
    TimePPT  
    PRO
       2023-02-15 17:38:37 +08:00
    随手写的,应该还有更简洁的写法
    songdg
        3
    songdg  
    OP
       2023-02-18 14:52:32 +08:00
    @TimePPT 谢谢帮助,我觉得还是写个函数来解决这个问题。
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