如何根據 Python 中另一個數據框的值更新數據框中列的值？

Question

df1
  | location | latitude
0 | NaN      | 41.0
1 | NaN      | 43.0
2 | NaN      | 72.0
3 | NaN      | 74.0

df2
  | location | min_latitude | max_latitude
0 | point_a  | 40.0         | 45.0
1 | point_b  | 70.0         | 75.0

如何根據latitude介於min_latitude和max_latitude之間的條件更新df1的location值，就像下面的結果一樣？

df1
  | location | latitude
0 | point_a  | 41.0
1 | point_a  | 43.0
2 | point_b  | 72.0
3 | point_b  | 74.0

我試過使用df1['location'].apply(lambda x: df2['location'] if df1['location'].between(df2['min_latitude'], df2['max_latitude']) else df1['location']) ，但它返回ValueError: Can only compare identically-labeled Series objects 。

Answer 1

您不需要使用 between，您可以使用布爾索引並獲得您想要的：

df1["location"][(df1["latitude"] > df2["min_lattitude"]["point_a"]) & (df1["latitude"] < df2["max_lattitude"]["point_a"])] = "point_a"

和 point_b 類似的東西。 你也可以通過遍歷一個點列表來做很多點。