Specification: Find the name of the continent with the highest average population by country.
Example input/output:
Input:
countries| name | population | continent |
|---|---|---|
USA | 328 | North America |
Canada | 37 | North America |
Ethiopia | 109 | Africa |
Kenya | 51 | Africa |
Output:
North AmericaPython - Imperative
def continent_by_population(countries):
continent_stats = defaultdict(lambda: [0, 0])
for country in countries:
continent = country['continent']
continent_stats[continent][0] += country['population']
continent_stats[continent][1] += 1
max_continent = None
max_average = None
for continent, [total, count] in continent_stats.items():
average = total / count
if max_average is None or max_average < average:
max_average = average
max_continent = continent
return max_continent
Python - Functional
def continent_by_population(countries):
continents = set([c['continent'] for c in countries])
populations_by_continent = [
(continent, [c['population'] for c in countries
if c['continent'] == continent])
for continent in continents
]
averages = [
(continent, sum(pops) / len(pops))
for continent, pops in populations_by_continent
]
return max(averages, key=lambda t: t[1])[0]
Python - Pandas
def continent_by_population(countries):
mean_pop = countries.groupby('continent').population.mean()
return mean_pop.index[mean_pop.argmax()]
R - Tidyverse
continent_by_population <- function(countries) {
countries %>%
group_by(continent) %>%
summarize(mean_pop = mean(population)) %>%
slice(which.max(mean_pop)) %>%
.$continent
}
SQL - SQLite
SELECT continent
FROM countries
GROUP BY continent
ORDER BY AVG(population) DESC
LIMIT 1
Datalog - Souffle
.decl average_population(Continent:symbol,Avg:number)
average_population(Continent,Avg):-
countries(Continent,_,_),
Total=sumPcountries(Continent,_,P),
Num_countries=countcountries(Continent,_,_),
Avg=TotalNum_countries.
continent_by_population(Continent):-
countries(Continent,_,_),
average_population(Continent,Max_avg),
Max_avg=maxAcountries(C,_,_),average_population(C,A).
Q - kdb+
averages:
select avg(population) by continent from countries;
continent_by_population:
(first select[>population] continent from averages) `continent