python之操作列表

编程
0 字 / 约 0 分钟
2020/1/31
  1. 用for遍历整个列表
python

>>> cells =['cellA', 'cellB', 'cellC', 'cellD'] 
>>> for cel in cells: 
... print(cel) 
... cellA cellB cellC cellD
  1. For循环中加入操作
python

>>> 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.
  1. For循环后加入操作
python

>>> 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
  1. For循环在某一范围"使用range()"
python
>>> 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

python

>>> cells = ['cellA', 'cellB', 'cellC', 'cellD','cellE','cellF','cellG'] 
>>> for i in range(0,7,2): 
... print(cells[i]) 
... cellA cellC cellE cellG
  1. 使用range()创建数字列表
python
>>> numbers = list(range(1,6)) 
>>> print(numbers) [1, 2, 3, 4, 5]

range()函数可以指定步长

python
>>> numbers = list(range(1,6,2)) 
>>> print(numbers) [1, 3, 5]
  1. 数字列表的简单计算
python
>>> 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
  1. 列表切片
python

>>> 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']
  1. 遍历切片
python
>>> cells = ['cellA', 'cellB', 'cellC', 'cellD','cellE','cellF','cellG'] 
>>> for cel in cells[:4]: 
... print(cel) 
... cellA cellB cellC cellD
  1. 复制列表
python
>>> cells = ['cellA', 'cellB', 'cellC', 'cellD','cellE','cellF','cellG'] 
>>> another = cells[:] 
>>> print(another) ['cellA', 'cellB', 'cellC', 'cellD', 'cellE', 'cellF', 'cellG']
  1. 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。
python
>>> dimenssions = (200, 300) 
>>> print(dimensions[0]) 200 
>>> print(dimensions[1]) 300
  1. 遍历元组
python
>>> dimensions = (200, 300) 
>>> for dim in dimensions: 
... print(dim) 
... 200 300
  1. 修改元组变量
python
>>> dimensions = (200, 300) 
>>> for dim in dimensions: 
... print(dim) 
... 200 300

重新定义

python
>>> dimensions = (400, 500) 
>>> for dim in dimensions: 
... print(dim) 
... 400 500