分类
python

Python之列表基础

  1. 定义列表
    python中用中括号[]表示列表,列表元素用逗号(,)隔开
    >>> cells = ['cellA','cellB','cellC']
    >>> print(cells)
    ['cellA', 'cellB', 'cellC']

    定义一个空的列表
    >>> cells = []
    >>> print(cells)
    []
  2. 索引介绍及访问列表元素
    python列表中,索引是从0开始的,而不是1,所以第一个元素索引为0。
    >>> cells = ['cellA','cellB','cellC']
    >>> print(cells[0])
    cellA
    >>> print(cells[1])
    cellB
    >>> print(cells[2])
    cellC
    >>> print(cells[-1]) #指定索引[-1]可以让python返回列表最后一个元素。
    cellC
    >>> print(cells[-2]) #指定索引[-2]可以让python返回列表倒数第二个元素。
    cellB
  3. 修改列表元素
    >>> cells = ['cellA','cellB','cellC']
    >>> print(cells)
    ['cellA', 'cellB', 'cellC']
    >>> cells[0] = 'blockA'
    >>> print(cells)
    ['blockA', 'cellB', 'cellC']
  4. 添加元素到列表”append”
    >>> cells = ['cellA','cellB','cellC']
    >>> cells.append('cellD')
    >>> print(cells)
    ['cellA', 'cellB', 'cellC', 'cellD']
  5. 列表中插入元素”insert”
    >>> cells = ['cellA','cellB','cellC']
    >>> cells.insert(0,'cellX')
    >>> print(cells)
    ['cellX', 'cellA', 'cellB', 'cellC']
  6. 删除列表中的元素”del”
    >>> cells = ['cellA','cellB','cellC']
    >>> del cells[0]
    >>> print(cells)
    ['cellB', 'cellC']
    >>> cells = ['cellA','cellB','cellC']
    >>> del cells[-1]
    >>> print(cells)
    ['cellA', 'cellB']
  7. 弹出列表中指定元素“pop()”
    >>> cells = ['cellA','cellB','cellC']
    >>> second_cell = cells.pop(1)
    >>> print('The second cell is '+ second_cell + '.')
    The second cell is cellB.
    >>> print(cells)
    ['cellA', 'cellC'] #索引[1]被弹出后已自动从列表中删除
  8. 根据索引值删除列表中元素“remove()”
    >>> cells = ['cellA','cellB','cellC','cellA']
    >>> cells.remove('cellA')
    >>> print(cells)
    ['cellB', 'cellC', 'cellA'] #revome只会删除第一个指定的值
  9. 永久性排序列表“sort()”
    >>> cells = ['cellB','cellD','cellC','cellA']
    >>> cells.sort()
    >>> print(cells)
    ['cellA', 'cellB', 'cellC', 'cellD']

    sort(reverse=True)可以反向排序
    >>> cells = ['cellB','cellD','cellC','cellC']
    >>> cells.sort(reverse=True)
    >>> print(cells)
    ['cellD', 'cellC', 'cellC', 'cellB']
  10. 临时性排序列表”sorted()”
    sorted不会永久改变列表顺序,只是临时的
    >>> cells = ['cellB','cellD','cellC','cellA']
    >>> print('original list is:');print(cells)
    original list is:
    ['cellB', 'cellD', 'cellC', 'cellA']
    >>> print('sorted list is:');print(sorted(cells))
    sorted list is:
    ['cellA', 'cellB', 'cellC', 'cellD']
    >>> print('original list is:');print(cells)
    original list is:
    ['cellB', 'cellD', 'cellC', 'cellA']
  11. 反转列表”reverse”
    >>> cells =['cellA', 'cellB', 'cellC', 'cellD']
    >>> print(cells)
    ['cellA', 'cellB', 'cellC', 'cellD']
    >>> cells.reverse()
    >>> print(cells)
    ['cellD', 'cellC', 'cellB', 'cellA']
  12. 获取列表长度”len”
    >>> cells =['cellA', 'cellB', 'cellC', 'cellD']
    >>> len(cells)
    4

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