How do I update the values of a column in a data frame based on the values of another data frame in Python?

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

How can I update the location values in df1 based on the condition that latitude is between min_latitude and max_latitude just like the result below?

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

I have tried using df1['location'].apply(lambda x: df2['location'] if df1['location'].between(df2['min_latitude'], df2['max_latitude']) else df1['location']) , but it returns ValueError: Can only compare identically-labeled Series objects .

Answer 1

You don't need to use between, you can use boolean indexing and get what you want with:

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

and something similar for point_b. You could do many points by iterating through a list of points as well.