Return of a function in Pyton

Question

How do I return only the list of this function without executing the print and input commands who are inside ?

def entrada_soma():
    parcela1 = list()
    parcela2 = list()
    print("Digite a opção desejada :")
    print("[1] - Valores pelo Teclado / [2] - Gerar aleatoriamente")
    entrada = int(input())
    print("Quantos inteiros cada sequência terá ?")
    n = int(input())
    if entrada == 1:
        print("Digite a sequência de inteiros da parcela 1 :")
        for c in range(0, n):
            x = int(input())
            parcela1.append(x)
        print("Digite a sequência de inteiros da parcela 2 :")
        for c in range(0, n):
            x = int(input())
            parcela2.append(x)
    else:
        print("Valores gerados para a parcela 1 :", end=' ')
        for c in range(0, n):
            parcela1.append(random.randint(0, 9))
            print(parcela1[c], end=' ')
        print()
        print("Valores gerados para a parcela 2 :", end=' ')
        for c in range(0, n):
            parcela2.append(random.randint(0, 9))
            print(parcela2[c], end=' ')

    print()
    return parcela1, parcela2

Answer 1

A function executes an algorithm that returns a value. Its initial function uses variables that need user interaction to inform what it wants. To leave only the function returning the lists, you will need:

1. Remove user information requests from function
2. The Function will receive the values of variables as parameters of function.

That is, you need to divide your current function into two parts, the first part being the "application" that will collect the necessary entries that will be passed as parameter to the function.

Based on your example, we would have that the function now predicts the receipt of 4 possible parameters def entrada_soma(entrada,n,x1,x2):.

The Function

def entrada_soma(entrada,n,x1,x2):
    parcela1 = list()
    parcela2 = list()
    if entrada == 1:
        for c in range(0, n):
            parcela1.append(x1)
        for c in range(0, n):
            parcela2.append(x2)
    else:
        for c in range(0, n):
            parcela1.append(random.randint(0, 9))
        for c in range(0, n):
            parcela2.append(random.randint(0, 9))
    return parcela1, parcela2

Note that the above function does not require anything else from the user, as this request will be separate from the function.

The Application using the function

The App will be responsible for collecting the necessary information to be passed to the function as a parameter and display the received result.

print("Digite a opção desejada :")
print("[1] - Valores pelo Teclado / [2] - Gerar aleatoriamente")
entrada = int(input())

print("Quantos inteiros cada sequência terá ?")
n = int(input())

x1 = 0  #  Declarando variáveis possíveis a serem utilizadas
x2 = 0  #  A segunda variável "x" que havia sido utilizada na função original

if entrada == 1:
    print("Digite a sequência de inteiros da parcela 1 :")
    x1 = int(input())
    print("Digite a sequência de inteiros da parcela 2 :")
    x2 = int(input())

p1, p2 = entrada_soma(entrada, n, x1, x2)

print("Valores gerados para a parcela 1 :", end=' ')
print(p1)
print("Valores gerados para a parcela 2 :", end=' ')
print(p2)

I tried to change the name of your variables as little as possible and I did not analyze the logic of your algorithm. Apparently it’s not working properly.

The function aims to reuse code. I do not see as good practice the fulfillment of requests to the user in the body of the function. The application that will call the function is that will be in charge of collecting the values to be passed to the function as parameter. The function must declare parameters that will be used in the body of the algorithm.

---

Below, let’s make an analogy with another code, say you had the next code and wanted to remove the requests from the function:

Function with prints and inputs

# Função com prints e requisições do usuário
def somaDoisNumeros():
    print('Soma de 2 números')
    print('Informe o primeiro número:')
    numero1 = int(input())
    print('Informe o segundo número:')
    numero2 = int(input())
    resultado = numero1 + numero2
    return resultado

# Aplicativo utilizando a função
soma = somaDoisNumeros()
print('A soma é:',soma)

Now let’s remove the prints and inputs from the function, passing the requests to be made to the user to the body of the "application"

Function without prints or inputs

# Função sem prints e sem requisições do usuário
def somaDoisNumeros(numero1, numero2):
    resultado = numero1 + numero2
    return resultado

# Aplicativo utilizando a função. Coleta entradas necessárias
print('Soma de 2 números')
print('Informe o primeiro número:')
n1 = int(input())

print('Informe o segundo número:')
n2 = int(input())

soma = somaDoisNumeros(n1, n2)
print('A soma é:',soma)

---

The main purpose of the function is to help us organize programs in pieces that correspond to how we imagine a solution of the problem.

Example to request user option

def lerOpcao():
    print("Informe como deseja gerar suas listas")
    print("[1] - Valores pelo Teclado")
    print("[2] - Gerar aleatoriamente")
    entrada = int(input())
    return entrada

This function lerOpcao() could be called while the user reported a value other than 1 or 2 as follows:

opcao = 0
# Garantir que seja informada umas das opções possíveis
while opcao not in [1,2]:
    opcao = lerOpcao()

This way, a function was created to request the user’s option, I’m not saying it is the best way, but you will do the functions according to your programming logic.

Function to return list of numbers entered manually

You could create a function to be used whenever you need the user to inform the list of the number that should appear in the sequence, n will be the number of the sequence, as in the following example:

def lerNumerosManuais(n):
    lista = []
    print(f'Informe os {n} números da lista')
    for i in range(0,n):
        print("Informe um número :", end=' ')
        valor = int(input())
        lista.append(valor)
    return lista

Would use the function lerNumerosManuais next form:

if opcao == 1:
    print("Digite a sequência de inteiros da parcela 1 :")
    parcela1 = lerNumerosManuais(n)

Function to return list of numbers when the option is Random

def geraNumerosAleatorios(n):
    lista = []
    for i in range(0,n):
        valor = random.randint(0, 9)
        lista.append(valor)
    return lista

Example of the call:

parcela1 = geraNumerosAleatorios(n)

I hope it helps.