[FIXED] How do I join 2 columns on Pandas?

Issue

I am working with two data frames that I joined using

 df = pd.concat([hc,nh], ignore_index=True, sort=False)

and now need to combine a few like-columns. For example:

Country   Country_ID  
1         
2         
             3
             4

How do I make it so it'd look like this:

Country
1
2
3
4        

I saw this post that is a similar question to mine, but the answer there didn't work for me...

Solution

Assuming you have a dataframe:

import pandas as pd
import numpy as np

df = pd.DataFrame({
    'Country': [1,2, None, None],
    'Country ID': [None, None, 3, 4]
})

Data from one column can be assigned to another one using np.where():

df['Country'] = np.where(df['Country'].isna(), df['Country ID'], df['Country'])

Answered By - Alexandra Dudkina