import pandas as pd

import matplotlib.pyplot as plt

import numpy as np

import helper

import sim$\_$parameters

def calculate$\_$number$\_$of$\_$samples$($df$,$ countries, sample$\_$ratio$)$:

$\text{'}\text{'}\text{'}$

function that returns a nested dictionary with the structure: 'Afghanistan' : $\{$less$\_5$ : $3\}$

$\text{'}\text{'}\text{'}$

population $=\{\}$ # dictionary, storing each country with its population

for country in countries:

# filter the dataframe to get the population of the current country

country$\_$row $=$ df$[$df$[\text{'}$country$\text{'}]==$ country$]$

population$[$country$]=$ country$\_$row$[\text{'}$population$\text{'}].$values$[0]$ # now each country has it's population

num$\_$samples$\_$country $=[]$ # list storing $($order of the countries in population$)$ the number of samples of each country

# calculate the number of samples for each country

for country in population:

num$\_$samples$\_$country.append$($int$(($population$[$country$]/$sample$\_$ratio$)//1))$ # floor value using $//1$ and casting into integer

# harcoded for speeding up process, TODO eliminate this line

num$\_$samples$\_$country $=[4,1,12]$

print$("$

Number of samples of each country we are going to use for the moment $($faster execution$)$:

$",$ num$\_$samples$\_$country$)$

# Calculate the number of samples of each age group inside each country

# nested dictionary key: country, value: dictionary with each age group the number of samples

num$\_$group$\_$samples$\_$inside$\_$country $=\{\}$ # eg: 'Afghanistan' : $\{$less$\_5$ : $3\}$

# TODO Calculate the values of the dictionary

# $-------------$

return num$\_$group$\_$samples$\_$inside$\_$country

Please complete the TODO section of this code.