Python如何实现动态数组

>>> test_list = [] # 创建名为test_list的空列表
>>> test_list.append("Hello")
>>> test_list.append("World")
>>> test_list
['Hello', 'World']
>>> test_list = ["Hello", "Array", 2019, "easy learning", "DataStructure"] # 重新给test_list赋值
>>> len(test_list) # 求列表的长度
5
>>> test_list[2] = 1024 # 修改列表元素
>>> test_list
['Hello', 'Array', 1024, 'easy learning', 'DataStructure']
>>>
>>> test_list.insert(1, "I love")  # 向列表中指定位置中插入一个元素
>>> test_list
['Hello', 'I love', 'Array', 1024, 'easy learning', 'DataStructure']
>>> test_list.append(2020) # 向列表末尾增加一个元素
>>> test_list
['Hello', 'I love', 'Array', 1024, 'easy learning', 'DataStructure', 2020]
>>>
>>> test_list.pop(1)  # 删除指定位置的元素
'I love'
>>> test_list.remove(2020) # 删除指定元素
>>> 
>>> test_list.index('Hello')  # 查找某个元素的索引值
0
>>> test_list.index('hello')  # 如果查找某个元素不在列表中，返回ValueError错误
Traceback (most recent call last):
 File "<pyshell#11>", line 1, in <module>
  test_list.index('hello')
ValueError: 'hello' is not in list
>>> 
>>> test_list.reverse() # 反转整个列表
>>> test_list
['DataStructure', 'easy learning', 2019, 'Array', 'Hello']
>>> test_list.clear()  # 清空列表
>>> test_list
[]

# -*- coding: utf-8 -*-
# @Time   : 2019-11-01 17:10
# @Author  : yuzhou_1su
# @ContactMe : https://blog.csdn.net/yuzhou_1shu
# @File   : DynamicArray.py
# @Software : PyCharm

import ctypes


class DynamicArray:
  """A dynamic array class akin to a simplified Python list."""

  def __init__(self):
    """Create an empty array."""
    self.n = 0       # count actual elements
    self.capacity = 1   # default array capacity
    self.A = self._make_array(self.capacity)   # low-level array

  def is_empty(self):
    """ Return True if array is empty"""
    return self.n == 0

  def __len__(self):
    """Return numbers of elements stored in the array."""
    return self.n

  def __getitem__(self, i):
    """Return element at index i."""
    if not 0 <= i < self.n:
      # Check it i index is in bounds of array
      raise ValueError('invalid index')
    return self.A[i]

  def append(self, obj):
    """Add object to end of the array."""
    if self.n == self.capacity:
      # Double capacity if not enough room
      self._resize(2 * self.capacity)
    self.A[self.n] = obj  # Set self.n index to obj
    self.n += 1

  def _resize(self, c):
    """Resize internal array to capacity c."""
    B = self._make_array(c)   # New bigger array
    for k in range(self.n):  # Reference all existing values
      B[k] = self.A[k]
    self.A = B     # Call A the new bigger array
    self.capacity = c  # Reset the capacity

  @staticmethod
  def _make_array(c):
    """Return new array with capacity c."""
    return (c * ctypes.py_object)()

  def insert(self, k, value):
    """Insert value at position k."""
    if self.n == self.capacity:
      self._resize(2 * self.capacity)
    for j in range(self.n, k, -1):
      self.A[j] = self.A[j-1]
    self.A[k] = value
    self.n += 1

  def pop(self, index=0):
    """Remove item at index (default first)."""
    if index >= self.n or index < 0:
      raise ValueError('invalid index')
    for i in range(index, self.n-1):
      self.A[i] = self.A[i+1]
    self.A[self.n - 1] = None
    self.n -= 1

  def remove(self, value):
    """Remove the first occurrence of a value in the array."""
    for k in range(self.n):
      if self.A[k] == value:
        for j in range(k, self.n - 1):
          self.A[j] = self.A[j+1]
        self.A[self.n - 1] = None
        self.n -= 1
        return
    raise ValueError('value not found')

  def _print(self):
    """Print the array."""
    for i in range(self.n):
      print(self.A[i], end=' ')
    print()

def main():
  # Instantiate
  mylist = DynamicArray()

  # Append new element
  mylist.append(10)
  mylist.append(9)
  mylist.append(8)
  # Insert new element in given position
  mylist.insert(1, 1024)
  mylist.insert(2, 2019)
  # Check length
  print('The array length is: ', mylist.__len__())
  # Print the array
  print('Print the array：')
  mylist._print()
  # Index
  print('The element at index 1 is :', mylist[1])
  # Remove element
  print('Remove 2019 in array:')
  mylist.remove(2019)
  mylist._print()
  # Pop element in given position
  print('Pop pos 2 in array:')
  # mylist.pop()
  mylist.pop(2)
  mylist._print()
if __name__ == '__main__':
  main()

The array length is: 5
Print the array：
10 1024 2019 9 8 
The element at index 1 is : 1024
Remove 2019 in array:
10 1024 9 8 
Pop pos 2 in array:
10 1024 8