Python pandas - new column's value if the item is in the list

Question

I want to create a new column in pandas dataframe. The first column contains names of countries. The list contains countries I am interested in (eg. in EU). The new colum should indicate if country from dataframe is in the list or not.

Below is the shortened version of the code:

import pandas as pd
import numpy as np

EU = ["Austria","Belgium","Germany"]

df1 = pd.DataFrame(data={"Country":["USA","Germany","Russia","Poland"], "Capital":["Washington","Berlin","Moscow","Warsaw"]})

df1["EU"] = np.where(df1["Country"] in EU, "EU", "Other")

The error I get is:

ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

I don't know what the problem is and how to solve it. What am I missing?

Answer 1

Use isin for check membership:

df1["EU"] = np.where(df1["Country"].isin(EU), "EU", "Other")
print (df1)
      Capital  Country     EU
0  Washington      USA  Other
1      Berlin  Germany     EU
2      Moscow   Russia  Other
3      Warsaw   Poland     EU