Adding a new column to a dataframe

[buran]

import pandas as pd
 
url='https://raw.githubusercontent.com/nytimes/covid-19-data/master/us-states.csv'
data = pd.read_csv(url, parse_dates=['date'])
data['DOW'] = data['date'].apply(lambda x: x.strftime('%A'))

# if you don't want to convert date columne:
# data = pd.read_csv(url)
# data['DOW'] = pd.to_datetime(data['date']).apply(lambda x: x.strftime('%A'))

print(data.head())

Output:
         date       state  fips  cases  deaths        DOW
0  2020-01-21  Washington    53      1       0    Tuesday
1  2020-01-22  Washington    53      1       0  Wednesday
2  2020-01-23  Washington    53      1       0   Thursday
3  2020-01-24    Illinois    17      1       0     Friday
4  2020-01-24  Washington    53      1       0     Friday

In the example I convert date column to datetime object when I read the csv file. In the comments - example if you do not want to convert it