Create empty string array python

In Python, the tendency is usually that one would use a non-fixed size list (that is to say items can be appended/removed to it dynamically). If you followed this, there would be no need to allocate a fixed-size collection ahead of time and fill it in with empty values. Rather, as you get or create strings, you simply add them to the list. When it comes time to remove values, you simply remove the appropriate value from the string. I would imagine you can probably use this technique for this. For example (in Python 2.x syntax):

>>> temp_list = []
>>> print temp_list
[]
>>> 
>>> temp_list.append("one")
>>> temp_list.append("two")
>>> print temp_list
['one', 'two']
>>> 
>>> temp_list.append("three")
>>> print temp_list
['one', 'two', 'three']
>>> 

Of course, some situations might call for something more specific. In your case, a good idea may be to use a deque. Check out the post here: Python, forcing a list to a fixed size. With this, you can create a deque which has a fixed size. If a new value is appended to the end, the first element (head of the deque) is removed and the new item is appended onto the deque. This may work for what you need, but I don't believe this is considered the "norm" for Python.

Prerequisite: List in Python 

As we know Array is a collection of items stored at contiguous memory locations. In Python, a List (Dynamic Array) can be treated as an Array. In this article, we will learn how to initialize an empty array of some given size. Let’s see different Pythonic ways to create an empty list in Python with a certain size.

Method 1: Initialize empty array using * Operator

In this example, we are creating different types of empty using an astrick(*) operator.

Python3

a = [0] * 10

print("Creating empty list of zeros: ", a)

b = [None] * 8

print("Creating empty list of None: ", b)

c =  [[0] * 4] * 3

print("Creating 2D empty list of zeros: ", c)

d = []

print("Creating empty list of zeros: ", d)

Output:

Creating empty list of zeros:  [0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
Creating empty list of None:  [None, None, None, None, None, None, None, None]
Creating 2D empty list of zeros:  [[0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]]
Creating empty list of zeros:  []

Method 2:  Create an empty list in python with a certain size using list comprehension

In this example, we are using Python List comprehension for 1D and 2D empty arrays.

Python3

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

print(a)

b = [[0] * 4 for i in range(3)]

print(b)

Output:

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

Method 3:  Create an empty list of a specific size in Python using a loop

In this example, we are using a Python loop for 1D and 2D empty arrays.

Python3

b= []

for x in range(5):

    b.append([[]])

print(b)

c = []

for x in range(5):

    c.append(0)

print(c)

Output:

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

Method 4:  Initialize empty array using Numpy

In this method, we are using the Numpy module to generate an empty matrix of 1D and 2D sizes using np.empty().

Python3

import numpy

a = numpy.empty(5, dtype=object)

print(a)

matrix = numpy.empty(shape=(2, 5), dtype='object')

print(matrix)

Output:

[None None None None None]

[[None None None None None]
 [None None None None None]]

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