5 Ways to Initialize a Python Array

Last Updated on April 23, 2021 by admin

An array, in the English language, refers to an ordered series of arrangements. In a programming language, an array can be defined as a collection of items stored at contiguous memory locations.

Python does not have built-in support for arrays (we can import them from the “array” module) but lists can be used instead. In this article, we will learn how we can initialize an empty array of a given size.

5 Ways to Initialize a Python Array

METHOD 1:


arr = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

print(arr)

Explanation: This is the most basic method of filling an empty list since everything is done manually. All we had to do is create a list, give it a name (arr in our case), and fill it with our desired values.

Output:

[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

METHOD 2

In this method, we will initialize a list using loops.


a=[]

a = [0 for x in range(10)]

print(a)

Explanation: In the first step we simply declared an empty list. Next, we iterated a for-loop within a given range, which in our case is 10, and stored the value 0 inside the empty list. Then we used the print statement by which we can prompt all elements of our newly filled list on the terminal.

Output:

[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

METHOD 3


a = [0] * 10

print(a)

Explanation: This method is quite similar to the one explained above since they only differ in syntax. All we had to do was create a variable for a list, “a” in our case, and assign the value we want the list to store. In this example, the program will store the value 0 in our list 10 times. It is as simple as that.

Output:

[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

Read more: How To Fix EOFError

METHOD 4

Here we will make use of a property called append(). The append() method in python adds a single item in a list that has already been defined. It does not create a new list rather it modifies the existing list by adding the item at the end of the list.


arr=[]

for i in range(0,10):

arr.append(0)

print(arr)

Explanation: First we created an empty list and named it “arr”. Next, we used a for-loop to iterate through the range, which is 10 in our case, and with each iteration, we told the program to add a 0 at the end of the list using the append() method. The resultant list will have 10 places, all filled with a 0.

Output:

[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

METHOD 5


import numpy

n = 10

arr = numpy.empty(n, dtype = object)

print(arr)

Explanation: This method makes use of the empty() method of the NumPy module of python. The empty() method is used to create a new array of given shapes and types, without initializing entries. The default value of the items in a list created by using the empty() method will be None.

Output:

[None NoneNoneNoneNoneNoneNoneNoneNone None]

This is about everything you need to know about initializing an array in python.

Read more: How to Check if File Exists Using Python?

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