Built-in functions

What if I ask you to define the maximum number in the list? Surely, using acquired knowledge, you can write a loop and check if the current element is greater/less than the previous and rewrite it, otherwise - continue... But in the case of big lists, this approach is very time-harmful... This task can be solved by using some built-in function.

min(x, y, ...) - minimum element of x, y, ...
max(x, y, ...) - maximum element of x, y, ...
abs(x) - absolute value of number
round(x, n) - rounds number x to n digits
pow(x, n) - x raised to the power n

For example, for countries we can calculate population density (population/area) and round result to 2 digits

countries = [["USA", 9629091, 331002651], ["Canada", 9984670, 37742154],

["Germany", 357114, 83783942], ["Brazil", 8515767, 212559417],

["India", 3166391, 1380004385]]

# calculate population density for countries

for i in range(len(countries)):

if type(countries[i]) is list:

print(countries[i][0], 'has population density:', round(countries[i][2]/countries[i][1], 2))


              1234567
            
countries = [["USA", 9629091, 331002651], ["Canada", 9984670, 37742154],
             ["Germany", 357114, 83783942], ["Brazil", 8515767, 212559417],
             ["India", 3166391, 1380004385]]
# calculate population density for countries
for i in range(len(countries)):
    if type(countries[i]) is list:
        print(countries[i][0], 'has population density:', round(countries[i][2]/countries[i][1], 2))

Compito

Swipe to start coding

In the people list, all the heights are in cm. Transform it into inches (divide by 2.54), round result to 2 digits and print message "Name has height of x inches".

Soluzione

# data

people = [["Alex", 178], ["Noah", 189], ["Peter", 175], ["John", 185], ["Michelle", 165]]

# print all the heights in inches with names

for i in range(len(people)):

if type(people[i]) is list:

print(people[i][0], 'has height of', round(people[i][1]/2.54, 2), 'inches')

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Sezione 7. Capitolo 1

# data

people = [["Alex", 178], ["Noah", 189], ["Peter", 175], ["John", 185], ["Michelle", 165]]

# print all the heights in inches with names

for i in range(len(people)):

if type(people[i]) is list:

print(people[i][0], 'has height of', _ _ _(people[_][_]/_ _ _, _) , 'inches')