python之操作列表
- 用for遍历整个列表
>>> cells =['cellA', 'cellB', 'cellC', 'cellD']
>>> for cel in cells:
... print(cel)
... cellA cellB cellC cellD
- For循环中加入操作
>>> cells =['cellA', 'cellB', 'cellC', 'cellD']
>>> for cel in cells:
... print('cells list include ' + cel + '.')
... cells list include cellA. cells list include cellB. cells list include cellC. cells list include cellD.
- For循环后加入操作
>>> cells =['cellA', 'cellB', 'cellC', 'cellD']
>>> for cel in cells:
... print('cells list include ' + cel + '.')
...
>>> print('that is all cells') cells list include cellA. cells list include cellB. cells list include cellC. cells list include cellD. that is all cells
- For循环在某一范围"使用range()"
>>> cells = ['cellA', 'cellB', 'cellC', 'cellD']
>>> for i in range(0,3):
#实际中 0<=i<3
... print(cells[i])
... cellA cellB cellC
range()函数可以指定步长
>>> cells = ['cellA', 'cellB', 'cellC', 'cellD','cellE','cellF','cellG']
>>> for i in range(0,7,2):
... print(cells[i])
... cellA cellC cellE cellG
- 使用range()创建数字列表
>>> numbers = list(range(1,6))
>>> print(numbers) [1, 2, 3, 4, 5]
range()函数可以指定步长
>>> numbers = list(range(1,6,2))
>>> print(numbers) [1, 3, 5]
- 数字列表的简单计算
>>> digitals = list(range(1,10))
>>> print(digitals) [1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> min(digitals) 1
>>> max(digitals) 9
>>> sum(digitals) 45
- 列表切片
>>> cells = ['cellA', 'cellB', 'cellC', 'cellD','cellE','cellF','cellG']
>>> print(cells[0:4]) #第一个至第3个 ['cellA', 'cellB', 'cellC', 'cellD']
>>> print(cells[:4]) #第一个至第3个 ['cellA', 'cellB', 'cellC', 'cellD']
>>> print(cells[2:]) #第3个至最后一个 ['cellC', 'cellD', 'cellE', 'cellF', 'cellG']
>>> print(cells[-2:]) #倒数第2个至最后一个 ['cellF', 'cellG']
- 遍历切片
>>> cells = ['cellA', 'cellB', 'cellC', 'cellD','cellE','cellF','cellG']
>>> for cel in cells[:4]:
... print(cel)
... cellA cellB cellC cellD
- 复制列表
>>> cells = ['cellA', 'cellB', 'cellC', 'cellD','cellE','cellF','cellG']
>>> another = cells[:]
>>> print(another) ['cellA', 'cellB', 'cellC', 'cellD', 'cellE', 'cellF', 'cellG']
- 定义元组 元组用圆括号表示,其元素不可更改,但可以重新定义,可以用索引访问。
>>> dimenssions = (200, 300)
>>> print(dimensions[0]) 200
>>> print(dimensions[1]) 300
- 遍历元组
>>> dimensions = (200, 300)
>>> for dim in dimensions:
... print(dim)
... 200 300
- 修改元组变量
>>> dimensions = (200, 300)
>>> for dim in dimensions:
... print(dim)
... 200 300
重新定义
>>> dimensions = (400, 500)
>>> for dim in dimensions:
... print(dim)
... 400 500