How to access a list that is inside another list in Python?

Question

I have a list that has within it another list with the students' names, and a list that has been divided into two more lists, representing the first note and the second note. For example:

[['Matheus', 'Julia', 'Eduardo'], [[9.4, 4.7, 3.2], [7.2, 8.3, 2.4]]]

I would like to know what I do to access each level of this list, to separately return the students' names, their first grade and second grade. I tried it this way:

nome = []
nota1 = []
nota2 = []

for i in range(0, 3):
   nome.append(str(input('Nome do Aluno: ')))
   nota1.append(float(input('Nota 1: ')))
   nota2.append(float(input('Nota 2: ')))
   print('\n')

notas = []
notas.append(nota1)
notas.append(nota2)

listaAlunos = []
listaAlunos.append(nome)
listaAlunos.append(notas)

for i in range(0, len(listaAlunos)):
   for j in range(0, 3):
      print(listaAlunos[i][j])

Answer 1

You could otherwise store as dictionary for example, but follows a possible answer to list within list:

for i, aluno in enumerate(listaAlunos[0]):
    print(aluno)
    print(f'nota 1 - {listaAlunos[1][0][i]}')
    print(f'nota 2 - {listaAlunos[1][1][i]}') 

The enumerate generates a 'counter' and we can use as index in the vector.

Entree:

Nome do Aluno: maria
Nota 1: 10
Nota 2: 20

Nome do Aluno: josé
Nota 1: 23
Nota 2: 24

Nome do Aluno: moises
Nota 1: 23
Nota 2: 45

Nome do Aluno: matusalem
Nota 1: 34
Nota 2: 45

Exit:

maria
nota 1 - 10.0
nota 2 - 20.0
josé
nota 1 - 23.0
nota 2 - 24.0
moises
nota 1 - 23.0
nota 2 - 45.0
matusalem
nota 1 - 34.0
nota 2 - 45.0

Answer 2

There are better ways to store your data as a list of dictionaries, or namedtuple lists. If the student model were more complex, it would still have the list of classes defined by the programmer.

But first...

Answering the question

listaAlunos = [['Matheus', 'Julia', 'Eduardo'], [[9.4, 4.7, 3.2], [7.2, 8.3, 2.4]]]

alunos, notas = listaAlunos

for i in range(len(alunos)):
    print(f"Aluno: {alunos[i]}")
    for n, notaAluno in enumerate(notas):
        print(f"Nota {n+1}: {notaAluno[i]}")

Other options

List of dictionaries

The form of storage would be

listaAlunos = []

for i in range(0, 3):
   nome = input('Nome do Aluno: ')
   nota1 = float(input('Nota 1: '))
   nota2 = float(input('Nota 2: '))
   listaAlunos.append({"aluno": nome, "nota1": nota1, "nota2": nota2})
   print('\n')

We would have as value

[{'aluno': 'Matheus', 'nota1': 9.4, 'nota2': 7.2}, 
 {'aluno': 'Julia', 'nota1': 4.7, 'nota2': 8.3}, 
 {'aluno': 'Eduardo', 'nota1': 3.2, 'nota2': 2.4}
]

To print

for aluno in listaAlunos:
    print(f"Aluno: {aluno['aluno']}")
    print(f"Nota 1: {aluno['nota1']}")
    print(f"Nota 2: {aluno['nota2']}")
    print()

The exit would be:

Aluno: Matheus
Nota 1: 9.4
Nota 2: 7.2

Aluno: Julia
Nota 1: 4.7
Nota 2: 8.3

Aluno: Eduardo
Nota 1: 3.2
Nota 2: 2.4

List of namedtuple

Gathering

from collections import namedtuple

listaAlunos = []

Aluno = namedtuple("Aluno", "aluno nota1 nota2")

for i in range(0, 3):
   nome = input('Nome do Aluno: ')
   nota1 = float(input('Nota 1: '))
   nota2 = float(input('Nota 2: '))
   listaAlunos.append(Aluno(aluno=nome, nota1=nota1, nota2=nota2))
   print('\n')

Stored data

[Aluno(aluno='Matheus', nota1=9.4, nota2=7.2),
 Aluno(aluno='Julia', nota1=4.7, nota2=8.3), 
 Aluno(aluno='Eduardo', nota1=3.2, nota2=2.4)
]

To print

for aluno in listaAlunos:
    print(f"Aluno : {aluno.aluno}")
    print(f"Nota 1: {aluno.nota1}")
    print(f"Nota 2: {aluno.nota2}")

The way out would be the same as before.

Another possibility would be to store in dictionary, where the key was the name of the student. The structure was like this:

{
 "Matheus": {
             "nota1": 9.4,
             "nota2": 7.2
            },
 "Julia": {
           "nota1": 4.7,
           "nota2": 8.3
          },
 "Eduardo": {
             "nota1": 3.2,
             "nota2": 2.4
            }
}

This is also feasible, but can complicate if you want to list students with a score of 1 less than 5, for example

For this case the list structure containing dictionaries is the most appropriate, as you can use the filter

Simply put, we would have:

listaAlunos = [{'aluno': 'Matheus', 'nota1': 9.4, 'nota2': 7.2}, {'aluno': 'Julia', 'nota1': 4.7, 'nota2': 8.3}, {'aluno': 'Eduardo', 'nota1': 3.2, 'nota2': 2.4}]

for aluno in filter(lambda aluno: aluno["nota1"] > 5, listaAlunos):
    print(aluno)

Being the result:

{'aluno': 'Matheus', 'nota1': 9.4, 'nota2': 7.2}

In the above case, lambda may be replaced by a function

def nota1_maior_que_cinco(aluno):
    return aluno["nota1"] > 5

for aluno in filter(nota1_maior_que_cinco, listaAlunos):
    print(aluno)
{'aluno': 'Matheus', 'nota1': 9.4, 'nota2': 7.2}

I hope I’ve helped