Python–初始化给定长度的空数组
原文:https://www . geeksforgeeks . org/python-initialize-empty-给定长度的数组/
先决条件:Python 中的列表
正如我们所知数组是存储在连续内存位置的项目集合。在 Python 中，列表 ( 动态数组)可以作为数组处理。在本文中，我们将学习如何初始化一个给定大小的空数组。
让我们看看不同的 Pythonic 方法来完成这项任务。
方法 1–
语法:
list1 = [0] * size
list2 = [None] * size
# initializes all the 10 spaces with 0’s
a = [0] * 10
# initializes all the 10 spaces with None
b = [None] * 10
# initializes all the 10 spaces with A's
c = ['A'] * 5
# empty list which is not null, it's just empty.
d = []
print (a, "\n", b, "\n", c, "\n", d);
Output:
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
[None, None, None, None, None, None, None, None, None, None]
['A', 'A', 'A', 'A', 'A']
[]
方法 2–使用类似 C 的循环并指定大小。
语法:
a = [0 for x in range(size)] #using loops
a = []
b = []
# initialize the spaces with 0’s with
# the help of list comprehensions
a = [0 for x in range(10)]
print(a)
# initialize multi-array
b = [ [ None for y in range( 2 ) ]
for x in range( 2 ) ]
print(b)
Output:
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
[[None, None], [None, None]]
方法 3–使用 Numpy 创建空数组。
import numpy
# create a simple array with numpy empty()
a = numpy.empty(5, dtype=object)
print(a)
# create multi-dim array by providing shape
matrix = numpy.empty(shape=(2,5),dtype='object')
print(matrix)
输出:
[None None None None None]
[[None None None None None]
[None None None None None]]
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