list value to a variable, Python

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I want to create a list, and assign to a variable the value referring to the positioning of that list

For example list = ["a", "b", "c"]

Let’s say the priest gives me the letter "c"

I want a variable n that gets the number 2

python list

3 answers

2

you can create a function that receives the list and the element you want to think will return to its position.

    def ref(lista, elemento):
        for i in range(len(lista)):
            if lista[i] == elemento:
                return i
        return False

    # exemplo de uso 

    lista = ['a','b','c']
    n = ref(lista,'c')
    print('n =', n)

if you do not find the element it returns a False.

  • But it turns out I want to draw a random element from a list, and assign its value to a variable. I really want the value of the position, in this example I put, I want the value "2" (which is the number of the position) in a variable

  • in the example I gave you put the list and put the element and it returns the position it is in the list, if it does not find it returns false. if you want a random value you can import Random and use Random.Choice(list) then it takes a random element from the list. in case I put the value of the position in variable n.

  • 2

    Python lists have the method .index who already does what you suggest. Also, for i in range(len...): and definitely not idiomatic for Python, and should not be present in an answer to advise beginners.

  • If there is something wrong with my answer let me know that I will try to help you in the best way possible.

2

# Importa o método choice do módulo random que gera elementos randômicos(aleatórios)

from random import choice

# Cria uma lista

lista = ['a', 'b', 'c']              

# utiliza o método random para retornar um elemento aleatório da sua lista

elemento = choice(lista)            

# Utiliza o metódo index dos objetos de tipo list ara retorna o índice do elemento retornado

indice = lista.index(elemento)   

# Imprime o elemento e seu índice

print(elemento, indice)


'''

Esse algoritmo só funciona se sua lista não possuir elementos de mesmo valor 
pois o metódo index dos objetos tipo list retorna
a primeira ocorrência do elemento.

Exemplo:

'''

lista = ['a', 'b', 'c', 'a']

elemento = 'a'

indice = lista.index(elemento)

print(elemento, indice)

'''

Retorna o índice de valor 0 e não 3 mesmo 'a' aparecendo tanto em indice 0 
como em 3, ou seja o método index retorna a
primeira ocorrência do elemento lembre-se disso

'''

0

An easier way for you to do that is :

 l=['nathan','guilherme','otavio','ana']

# Lista que irá receber o indice
lista_enumerada = []

# for com enumerate, para que possamos ver o seu indice
for a,b in enumerate(l):
    lista_enumerada.append(a) # adicionando o valor a(indice) a lista

#armazenamento da escolha randomica
choice = random.randint(0,3)
n = l[choice] # Random na lista principal
print(n)
print(lista_enumerada[choice])

  • Instead of enumerate, a simpler way to have the index list is: lista_enumerada = list(range(len(l)))

  • Thanks! I had not thought to use this method of len to have a list only of indices, I only learned the form of the enumerate. This will facilitate my next Cod’s. Thank you very much

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