Python quiz (list as argument)

Programming Python
#1

Please guide how to solve this

def double_list(numbers):
return 2 * numbers

numbers = [1, 2, 3]
print(double_list(numbers))

#2

First, make sure you get the indentation right. Maybe you did, maybe you did not, but put your code into blocks using the </> key:

def double_list(numbers):
  return 2 * numbers

numbers = [1, 2, 3]
print(double_list(numbers))

If you run this, I get

[1, 2, 3, 1, 2, 3]
#3

I am confused why it gives… [1, 2, 3, 1, 2, 3]

not [2, 4, 6]??

#4

I’m not sure what the history of it is, but operator * just does this with lists. It does something similar if you use it with a string:

IPython 7.30.1 -- An enhanced Interactive Python. Type '?' for help.

In [1]: a = "a" * 3

In [2]: a
Out[2]: 'aaa'
#5

operator * doesn’t perform a matrix multiplication with lists. It specifies a number of repetitions of the list elements

With the string example provided by Rob, a string is treated as a list of characters, so similarly "abc" * 2 yields "abcabc"

#6

The issue with your code is that it’s doubling the number of elements by repeating entire list, not doubling each individual element value in the list.

To achieve [2, 4, 6] the code should be like :

def double_list(numbers):
  return list(map(lambda i: 2 * i, numbers))

numbers = [1, 2, 3]
print(double_list(numbers))

OR

def double_list(numbers):
  return [2 * i for i in numbers]

numbers = [1, 2, 3]
print(double_list(numbers))

Hope, this helps!
Thanks.