You doubt about multiplying items in a list

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You doubt about multiplying items in a list

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#1 by (3 votes)

3

I'm doing an exercise in Codecademy, specifically this one: Modify each element of a list in a function The case, that the code that I'm trying to use is this:

n = [3, 5, 7]
def doble_lista(x):
for i in range(0, len(x)):
x[i]=x[i]*2
return x

print doble_lista(n)

And I always get the same error:

File "python", line 5 x [i] = x [i] * 2 ^ IndentationError: expected an indented block

I have already tried to completely rewrite the code, I have asked in the official forums of the page and they have not been able to answer me.

python

asked by Feror 03.08.2016 в 15:07

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1 answer

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score 3 · Accepted Answer

Python recognizes the blocks of code by their level of indentation, in fact, the same interpreter tells you the error IndentationError on line 5.

As you currently have the code, I doubt it will be executed, since after each : when writing a sentence, Python expects a different indentation level than the one that contains the line with : , I explain:

This is your current code:

n = [3, 5, 7]
def doble_lista(x):
for i in range(0, len(x)):
x[i]=x[i]*2
return x

print doble_lista(n)

Indented would finally look like this:

n = [3, 5, 7]
def doble_lista(x):
    for i in range(0, len(x)):
        x[i]=x[i]*2
    return x

print doble_lista(n)

This last one works well.

Going a little deeper, why is this happening? As I said earlier, Python recognizes indentation levels as blocks of code, example:

def DiHola():
print "Hola"

It does not work as we expect, because the definition of the method DiHola() is at the same level as the print , the correct thing is to indentate even for a space, to define the block of code:

def DiHola():
  print "Hola"

So, the more blocks we have, we have to indentate:

def EjecutaAlgo():
    nombre = "NaCl"   # Todas las lineas que no aplican un bloque de indentado
    for s in nombre:  # van al mismo nivel, ejemplo estas dos.
        print s

And so on, all this is in the Python programming guides PEP .

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