Function Returning Multiple Values in Python 2.7

Question

It’s my first post on this forum, so I apologize in advance for any etiquette error.

I’m trying to implement a function in Python 2.7 that returns me a random element from a list or a sublist of random elements of certain size. My idea for implementation was this:

def pegaRandom(vetor,k=1):
    n = len(vetor)
    i = randrange(n)
    retorno = vetor[i]
    if k==1:
        return retorno
    else:
        vetor2 = list(vetor)
        vetor2.pop(i)
        return retorno, pegaRandom(vetor2,k-1)

My expected behavior was that the function would return me a sublist when k>1, but instead I have something like:

>>> pegaRandom(range(1,50),4)
(41, (37, (45, 26)))
>>> pegaRandom(range(1,50),10)
(15, (5, (21, (8, (39, (35, (19, (11, (12, 2)))))))))

Answer 1

Jonah,

This is happening because when there are two or more returns in a function, Python returns all the data in a tuple (tuple) format, see this example:

def multiploRetorno():
  return 1,2

multiplo = multiploRetorno()

print(type(multiplo), multiplo)

https://repl.it/repls/ElderlySimultaneousOutcomes

---

There is the possibility of receiving this return in several variables, when done in this way, the return ceases to be the tuple:

def multiploRetorno():
  return 1,2

primeiro, segundo = multiploRetorno()

print(primeiro)
print(segundo)

https://repl.it/repls/JoyfulRosyCharacters

---

Therefore, as its function has two recursion returns, these tuples are generated, one inside the other.

---

So that your function returns a list when k > 1, you can do as follows:

from random import randrange

def geraIndiceAleatorio(vetor):
  return randrange(len(vetor))

def pegaRandom(vetor,k=1):
  if k==1:
    return vetor[geraIndiceAleatorio(vetor)]
  else:
    retorno = []
    vetor2 = vetor[:]

    for j in range(k):
      indice = geraIndiceAleatorio(vetor2)
      retorno.append(vetor2[indice])
      vetor2.pop(indice)

    return retorno

print(pegaRandom(range(1,50)))

print(pegaRandom(range(1,50),1))

print(pegaRandom(range(1,50),4))

print(pegaRandom(range(1,50),10))

https://repl.it/repls/IdenticalGrippingExperiment