1.2数据类型(list)

Posted 2020-09-30 yangyangchunchun

列表创建

创建一个列表，只要用逗号分隔不同的数据项使用方括号括起来即可，例如：

first_list = ["hello","python",1900,1970]

列表访问

使用下标索引访问列表中的值，也可通过方括号进行截取。例如：

>>> first_list = ["hello","python",1900,1970]
>>> first_list[0]
‘hello‘
>>> first_list[1:3]
[‘python‘, 1900]

列表更新

可以索引对列表的数据项进行修改或更新，也可用append方法来增加列表项，例如：

>>> first_list = ["hello","python",1900,1970]
>>> first_list[1] = "yangyang"
>>> first_list
[‘hello‘, ‘yangyang‘, 1900, 1970]

append例子，例如：
>>> first_list = ["hello","python",1900,1970]

>>> first_list.append(2017)

>>> first_list
[‘hello‘, ‘yangyang‘, 1900, 1970, 2017]

列表元素删除

使用del删除列表中的元素，例如：

>>> first_list = ["hello","python",1900,1970]
>>> del first_list[3]
>>> first_list
[‘hello‘, ‘python‘, 1900]

列表截取

>>> first_list = ["hello","python",1900,1970]
>>> first_list[1]
‘python‘
>>> first_list[-2]
1900
>>> first_list[1:3]
[‘python‘, 1900]
>>> first_list[1:]
[‘python‘, 1900, 1970]
>>> first_list[-1:-3:-1]
[1970, 1900]

列表操作符：+、*、[]、[:]、in、not in、for i in list

 a = ["hello","python"],b = ["hello","yangyang"]

操作符	描述	实例
+	组合	>>> a = ["hello","python"] >>> b = ["hello","yangyang"] >>> a + b [‘hello‘, ‘python‘, ‘hello‘, ‘yangyang‘]
*	重复	>>> a * 4 [‘hello‘, ‘python‘, ‘hello‘, ‘python‘, ‘hello‘, ‘python‘, ‘hello‘, ‘python‘]
[]	索引	>>> a[0] ‘hello‘
[:]	截取	>>> a[0:2] [‘hello‘, ‘python‘]
in	成员运算符，元素在列表中返回True	>>> "hello" in a True
not in	成员运算符，元素不在列表中返回True	>>> "world" not in a True
for i in list	迭代	>>> for i in a: print i hello python