Python之列表基础
- 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) []
- 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
- 修改列表元素
>>> cells = ['cellA','cellB','cellC']
>>> print(cells) ['cellA', 'cellB', 'cellC']
>>> cells[0] = 'blockA'
>>> print(cells) ['blockA', 'cellB', 'cellC']
- 添加元素到列表"append"
>>> cells = ['cellA','cellB','cellC']
>>> cells.append('cellD')
>>> print(cells) ['cellA', 'cellB', 'cellC', 'cellD']
- 列表中插入元素"insert"
>>> cells = ['cellA','cellB','cellC']
>>> cells.insert(0,'cellX')
>>> print(cells) ['cellX', 'cellA', 'cellB', 'cellC']
- 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']
- 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
- 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
- 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']
- 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']
- 反转列表"reverse"
>>> cells =['cellA', 'cellB', 'cellC', 'cellD']
>>> print(cells) ['cellA', 'cellB', 'cellC', 'cellD']
>>> cells.reverse()
>>> print(cells) ['cellD', 'cellC', 'cellB', 'cellA']
- 获取列表长度"len"
>>> cells =['cellA', 'cellB', 'cellC', 'cellD']
>>> len(cells) 4