Nested Lists

A nested list is a list that contains another list, in other words it is a list of lists. It is also referred to as a multi-diminsional array.

nested_list = [['John', '50'], ['Mark', '40'], ['Ali', '24']]
print (len(nested_list))
#note that lenght of this nested list is 3, since we have 3 inner lists within the outer one

3

print (nested_list[0])

['John', '50']

print (nested_list[2][0])

Ali

# Let's iterate over this nested lists
for inner in nested_list:
    print (inner)

['John', '50']
['Mark', '40']
['Ali', '24']

# let's check value of inner so far
inner

['Ali', '24']

 # then let's iterate over all values within last nested list which is stored in the variable 'inner' at the moment
for value in inner:
    print (value)

Ali
24

# Now let's iterate over all values within last nested list which is stored in the variable 'inner' at the moment
for inner in nested_list:
    for value in inner:
        print (value)

John
50
Mark
40
Ali
24

Here we solve a solution for a problem from HackerRank at https://www.hackerrank.com/challenges/nested-list/problem the problem is an application on the use of nested list

# Let's initiate a dictionary so, all names that share the same score can be listed under the same key
score_dic = {}

for _ in range(int(input())):
    name = input()
    score = float(input())
    if score in score_dic:
        score_dic[score].append(name)
    else:
        score_dic[score] = [name]

# We need to convert that dictionary to new list sorted on keys
score_list = list(score_dic.items())
score_list.sort()
next_min = score_list[1][1]

# if we have mutltiple names then sort them alphabetically
next_min.sort()

# print the output by unzip the results using *
print (*next_min, sep = "\n")