How can I write the Python code to find the sum of values of a column in a Pandas DF for a specific row value?

Question

Pandas dataframe containining a few columns. Let's say years, production, num of units, price per unit.

I know how to get total of production for all the existing years in the DF using the sum() function.

Now I want to find the production for a specific year, let's say 2014. Now the years repeat in the dataframe. How do I write code to find the sum of all the values of production in the dataframe when year = 2014?

Do I use the groupby function? But how do I do that effectively to achieve this result?

Thank you!

Answer 1

Using arbitrary values for the variables that you listed,

import pandas as pd

years = list(range(2010, 2020))
years.extend([2014, 2014])
production = list(range(12))
num = list(range(12))
price = list(range(12))

df = pd.DataFrame({'years':years, 'prod': production, 'num': num,\
        'price': price})
answer = df[df['years'] == 2014]['prod'].sum().item()

print(answer)