CODEWITHSUNDEEP
pythonrandom
user3078335
user3078335

Reputation: 781

What does this statement really do?

I am new to python. Found a code online I am trying to understand. Can someone please help me understand what the following statement actually does? 

    self.record = [random.choice([0.0, 1.0]) for _ in range(10)]

Upvotes: 2

Views: 124

Answers (2)

SethMMorton
SethMMorton

Reputation: 48725

random.choice([0.0, 1.0])

The random.choice method will randomly pick an element of a given sequence. Here, it will randomly pick 0.0, or 1.0.

range(10)

This function will create a 10 element list (or iterable on python3)

[function() for _ in range(10)]

This is a list comprehension that will call a function 10 times, and place the results in a list. The _ is a python convention meaning "I need a variable here, but I won't use it's value"

[random.choice([0.0, 1.0]) for _ in range(10)]

This creates a list 10 elements long, where each element is either 0.0 or 1.0, randomly chosen.

self.record = [random.choice([0.0, 1.0]) for _ in range(10)]

This places the 10 element list into the instance variable record inside your current class.

It is equivalent to the following code

self.record = []
for _ in range(10):
    num = random.choice([0.0, 1.0])
    self.record.append(num)

Upvotes: 10

Karl Knechtel
Karl Knechtel

Reputation: 61498

It means what it says:

self.record  =                    [                        random.
#self.record shall be a name for: a list consisting of one random 
choice(                     [0.0, 1.0]) for _
#choice taken from the list [0.0, 1.0], for each value (which we don't care about)
in  range(                                  10)]
#in a range from 0 up to but not including 10.

Upvotes: 1

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