目录
数字类型的内置方法
整型/浮点型
| 加 | + |
|---|---|
| 减 | - |
| 乘 | * |
| 除 | / |
| 取余 | % |
| 余数取整 | // |
字符串类型的内置方法
| 掌握 | 熟悉 | 了解 |
|---|---|---|
| 按索引取值 ,strs[0] | lstrip,rstrip | find,rfind |
| 切片,str[::-1] | lower,upper | index,rindex |
| 长度,len[strs] | startswith,endswith | count |
| 成员运算,print{" 'llo' in strs"} | rsplit | center,ljust,rjust,zfill |
| 移除空白, strs.strip() | join | expandtabs |
| 切割,strs.split() | replace | captalize,swapcase,title |
| 循环,for i in strs: | isdigit | is |
掌握
a = "Hello World"
-
按索引取值:
print{a[0]} # H '''
总结:
1. 索引取值可以根据索引随时拿到字符串中任意一个字符.在工作中经常使用
''' -
切片
print{a[::-1]}
print(a[-1:-6:-1]) # dlroW olleH
# dlroW '''
总结:
1. 切片不仅可以截取字符串中的任意一部分,同时也可以将字符串进行反转操作.
''' -
长度,len()
print(len(a)) # 11 '''
总结:
1. 经常会根据字符串的长度 获取对应索引.在工作中经常使用.
''' -
成员运算,in/ not in
print("ello" in a) # True -
移除空白,strip,lstrip,rstrip
b = " dajiahao!wo jiao panlifu "
print(b.strip()) # dajiahao!wo jiao panlifu 默认直接删除字符串两端的空白 print(b.strip(" adwuflinp"))
# jiahao!wo jiao 直接从两端进行删除,只要传参的字符串中包含b字符串两端的字符,即可删除,没有则停止 # lstrip 左移除
print(b.lstrip())
print(b.lstrip(" jadu")) # dajiahao!wo jiao panlifu
# iahao!wo jiao panlifu # rstrip 右移除
print(b.rstrip())
print(b.rstrip(" aflui")) # dajiahao!wo jiao panlifu
# dajiahao!wo jiao pan -
切割, split,rsplit
print(a.split(" ",1))
# ['Hello', 'World'] print(a.split("o",2))
print(a.split("o")) # ['Hell', ' W', 'rld']
# ['Hell', ' W', 'rld'] # rsplit 右切割
print(a.rsplit())
# ['Hel', 'o Wor', 'd'] -
for循环
for i in a:
print(i) '''
H
e
l
l
o W
o
r
l
d
'''
熟悉
-
大小写, lower/upper
print(a.lower()) # hello world print(a.upper()) # HELLO WORLD '''
总结:
1. 通常在输入验证码的时候,不区分大小写.可能就是将对应的字符串统一变成了大写或小写
''' 判断区间内的首字母是否相同, startswith,endswith
print(a.startswith('r',0,len(a)))
# False
print(a.startswith('H',0,len(a)))
# True
print(a.endswith('e',0,len(a)))
# False
print(a.endswith('d',0,len(a)))
# True
'''
总结:
1. startswith,它可以判断区间内(顾头不顾尾)首字母是否为指定字符,返回bool值
2. endswith,它可以判断区间内(顾头不顾尾)尾字母是否为指定字符,返回bool值
'''
-
连接,join
test_list = ["etc","plf","lt","xs","cd"]
print("/".join(test_list)) # etc/plf/lt/xs/cd print('/'.join(a)) # h/e/l/l/o/ /w/o/r/l/d '''
总结:
1. 用来连接各个元素,一般用于路径的拼接
''' -
替换replace
print(a.replace("o","P")) # HellP WPrld '''
总结:
1. 将字符串中的字符替换成指定字符
''' -
判断是否为数字isdigit
print(a.isdigit()) # False test_str = "123"
print(test_str.isdigit()) # True '''
总结:
1. 判断字符串中是否全是数字
2. 注意:
当数字字符串中含有空格时,isdigit依然会返回True,因此我们使用数字时,一定要记得将空格替换掉!
'''
了解
-
查找 find,rfind
print(a.find("H")) # 0 print(a.find("d")) # 10 print(a.find("p")) # -1 print(a.find("ell")) # 1 '''
总结:
1. 当传入对应字符时,返回对应字符的下标.如果没有对应字符,则返回-1
2. 当传入字符串时,返回对应字符串第一个字符的下标.如果没有,则返回-1
''' -
index,rindex
print(a.index("H")) # 0 print(a.index("d")) # 10 print(a.index("p")) # 抛异常,程序中断 print(a.index("ell")) # 1 '''
总结:
1. 当传入对应字符时,返回对应字符的下标.如果没有对应字符,则抛异常
2. 当传入字符串时,返回对应字符串第一个字符的下标.如果没有,则抛异常
3. 与find相比,find的方式更加友好
''' -
count,字符串出现的次数
print(a.count("o")) # 2 -
center,ljust,rjust,zfill
# center 居中
print(a.center(30,"*")) # *********Hello World********** # ljust 居左
print(a.ljust(30,"*")) # Hello World******************* # rjust 居右
print(a.rjust(30,"*")) # *******************Hello World # zfill 默认以0填充
print(a.zfill(30))
# 0000000000000000000Hello World -
expandtabs, 设置制表符距离,默认为8
print("aaa\tbbb".expandtabs()) # aaa bbb print("aaa\tbbb".expandtabs(4)) # aaa bbb -
capitalize,swapcase,title
print(a.capitalize()) # Hello world print(a.swapcase()) # hELLO wORLD a = "hello world"
print(a.title())
# Hello World
列表的内置方法
作用：多个装备、多个爱好、多门课程、甚至是多个女朋友
定义：[]内可以有多个任意类型的值，逗号分隔元素
plf = ["name","age","sex","tank"]
print(plf)
方法：
| 增 | 删 | 改 | 查 |
|---|---|---|---|
| append(元素) | del 列表 | my_list[下标]="修改内容" | in/not in |
| extend(列表) | pop() | count(元素) | |
| insert(位置,"元素") | remove("元素") | index("元素") | |
| clear() | |||
存一个值or多个值： 多个值
有序or无序： 有序
可变or不可变：可变
可变or不可变： 可变
增
-
追加 , append
a = ["plf","lt","xs","cd"]
a.append('www')
print(a) # ['plf', 'lt', 'xs', 'cd', 'www'] -
增加列表
a = ["plf","lt","xs","cd"]
b = ["ls","ww","zhy"]
a.extend(b)
print(a) # ['plf', 'lt', 'xs', 'cd', 'ls', 'ww', 'zhy'] -
插入数据
a = ["plf","lt","xs","cd"]
a.insert(1,"www")
print(a) # ['plf', 'www', 'lt', 'xs', 'cd']
删
-
删除列表
a = ["plf","lt","xs","cd"]
a.insert(1,"www")
del a
print(a) '''
NameError Traceback (most recent call last)
<ipython-input-16-71b7731a4ef0> in <module>
2 a.insert(1,"www")
3 del a
----> 4 print(a) NameError: name 'a' is not defined
''' -
pop()
a = ["plf","lt","xs","cd"]
b = a.pop()
print("a的值%s\n%s"%(a,b)) '''
a的值:['plf', 'lt', 'xs']
b的值:cd
''' -
remove("元素")
a = ["lt","plf","lt","xs","cd","cd"]
a.remove("cd")
a.remove("lt")
print("a的值:%s"%(a)) '''
a的值:['plf', 'lt', 'xs', 'cd']
'''
改
-
根据下标更改
a = ["lt","plf","lt","xs","cd","cd"]
a[0] = "gunkai"
print("a的值:%s"%(a)) '''
a的值:['gunkai', 'plf', 'lt', 'xs', 'cd', 'cd']
'''
查
-
in/not in 是否在
a = ["lt","plf","lt","xs","cd","cd"]
print(bool("xxxx" in a))
print(bool("xxxx" not in a)) '''
False
True
''' -
count(元素)，元素出现个数
a = ["lt","plf","lt","xs","cd","cd"]
print(a.count("lt")) '''
2
''' -
index("元素") ，索引
a = ["lt","plf","lt","xs","cd","cd"]
print(a.index("lt")) '''
0
'''
列表的函数
-
len()，长度
a = ["lt","plf","lt","xs","cd","cd"]
print(len(a)) '''
6
''' -
max(list) ，返回列表元素最大值
a = ["lt","plf","lt","xs","cd","cd"]
b = ["plf","zj","xn","lt"]
c = [1,200,3,4,5,6,7,8,9,100,111]
print(max(a))
print(max(b))
print(max(c)) '''
xs
zj
200
''' # min(list) 同理,返回列表元素最小值 -
list(seq)，强制类型转化
a = "hello,world"
b = (1,2,3,4,5,6)
print(list(a))
print(list(b)) '''
['h', 'e', 'l', 'l', 'o', ',', 'w', 'o', 'r', 'l', 'd']
[1, 2, 3, 4, 5, 6]
''' '''
总结：
1. 可以强制类型转化 '''
其他
-
clear，清除
name_list = ['nick', 'jason', 'tank', 'sean']
name_list.clear() print(f"name_list: {name_list}") '''
name_list: []
''' -
copy，拷贝/深拷贝
name_list = ['nick', 'jason', 'tank', 'sean'] print(f"name_list.copy(): {name_list.copy()}") '''
name_list.copy(): ['nick', 'jason', 'tank', 'sean']
''' '''
总结：
1. 复制一个与原列表相同的列表 ''' -
reverse， 反转
name_list = ['nick', 'jason', 'tank', 'sean']
name_list.reverse() print(f"name_list: {name_list}") '''
name_list: ['sean', 'tank', 'jason', 'nick']
''' '''
总结：
1. 翻转排序 ''' -
sort，排序
a = [2113,3123,4,31,115,17,82,123,55,21]
a.sort()
print(a)
a.sort(reverse=True)
print(a)
'''
[4, 17, 21, 31, 55, 82, 115, 123, 2113, 3123]
[3123, 2113, 123, 115, 82, 55, 31, 21, 17, 4]
''' ''' 总结：
1. sort()排序后，没有返回值。因此不能这样打印：print(info.sort())
2. sort()方法中，可以添加翻转等操作 '''
字典的内置方法
作用：当列表存很多元素时，列表会显示很乱，所有有了字典
定义方式：{} 内以逗号分隔开多个键值对 key:value的值，key一般为字符串,value可以为任意对象
a_dict = {
'name':'PLF',
'age':20，
'height':165,
'hobby_list':["ch","pd",'watch']
}
方法：
| 增 | 删 | 改 | 查 |
|---|---|---|---|
| info['键'] = 数据 | del | info["键"] = 要修改的元素 | print(info["键"]) |
| update() | pop() | print(info.get("不存在的键")) | |
| fromkeys() | popitem() | for key,value in info.itmes() | |
| setdefault() | keys(),values(),items() | ||
存一个值or多个值：多个值，且值为不可变类型
有序or无序：无序
增
-
info['键'] = 数据
a = {"name":"plf","age":"20","sex":"nan"}
a["address"] = "Chinese"
print(a) '''
{'name': 'plf', 'age': '20', 'sex': 'nan', 'address': 'Chinese'}
''' -
update()
a = {"name":"plf","age":"20","sex":"nan"}
b = {"address":"Chinese"}
a.update(b)
print(a) '''
{'name': 'plf', 'age': '20', 'sex': 'nan', 'address': 'Chinese'} ''' -
fromkeys()
c_dic = dict.fromkeys(['name','age','sex'],None)
print(c_dic) '''
{'name': None, 'age': None, 'sex': None}
''' -
setdefault()
# dic之setdefault()，有指定key不会改变值；无指定key则改变值
dic = {'a': 1, 'b': 2} print(f"dic.setdefault('a'): {dic.setdefault('a',3)}")
print(f"dic: {dic}")
print(f"dic.setdefault('c'): {dic.setdefault('c',3)}")
print(f"dic: {dic}") '''
dic.setdefault('a'): 1
dic: {'a': 1, 'b': 2}
dic.setdefault('c'): 3
dic: {'a': 1, 'b': 2, 'c': 3}
'''
删
-
del
dic = {'a': 1, 'b': 2}
del dic['a'] print(dic) del dic
print(dic) '''
{'b': 2} ---------------------------------------------------------------------------
NameError Traceback (most recent call last)
<ipython-input-69-aded9265c051> in <module>
4 print(dic)
5 del dic
----> 6 print(dic) NameError: name 'dic' is not defined ''' -
pop()
# dic之删除pop()
dic = {'a': 1, 'b': 2}
dic.pop('a') # 指定元素删除 print(f"dic.pop('b'): {dic.pop('b')}")
print(f"dic.get('a'): {dic.get('a')}") '''
dic.pop('b'): 2
dic.get('a'): None ''' -
popitem()
dic = {'a': 1, 'b': 2} print(f"dic.popitem(): {dic.popitem()}") # 随机删除一个元素，无法指定 '''
dic.popitem(): ('b', 2) '''
改
-
根据key修改value
a = {"name":"plf","age":"24","sex":"boy"}
a["name"] = "cd"
print(a) '''
{'name': 'cd', 'age': '24', 'sex': 'boy'}
'''
元组的内置方法
作用：类似于列表，只不过元祖只能取不能更改
定义方式：() 内用逗号隔开任意数据类型的元素
a = ("plf","lt","xs","cd")
print(a)
'''
('plf', 'lt', 'xs', 'cd')
'''
方法：
| 索引取值 info["key"] |
|---|
| 切片 info["key"] |
| 长度 len(info) |
| 成员运算 in 和 not in |
| 循环 |
| count |
| index |
存储一个值 or 多个值：多个值
有序 or 无序：有序
可变 or 不可变：无
集合类型内置方法
作用：存多个值，为了集合之间做运算
-
定义方式：
s = set()
s = {1,2,3,4,5,1} -
方法
-
优先掌握
-
去重
a = [5, 2, 5, 1, 4, 3, 4,1,0,2,3,8,9,9,9]
print(list(set(a))) #将去掉重复的项后，再重新转成list '''
[0, 1, 2, 3, 4, 5, 8, 9] ''' -
并集
a = {1,2,3}
b = {2,3,4}
c = a|b
print(c) '''
{1, 2, 3, 4}
''' -
交集
a = {1,2,3}
b = {2,3,4}
c = a&b
print(c) '''
{2, 3}
''' -
差集
a = {1,2,3}
b = {2,3,4}
print(a-b)
print(b-a) '''
{1}
{4}
''' -
对称差集
a = {1,2,3}
b = {2,3,4}
print(a^b) '''
{1, 4}
''' -
父集 ( 判断 )
a = {1,2,3}
b = {2,3,4}
print(a > b)
a = {1,2,3,4}
print(a > b) '''
False
True
''' -
子集
a = {1,2,3}
b = {2,3,4}
print(a < b)
a = {2,3}
print(a < b) '''
False
True
''' -
==
a = {1,2,3,4}
b = {1,2,3,4}
print(a == b) a = {1,2,3}
print(a == b) '''
True
False
'''
-
-
需要掌握
-
add 添加元素
s = {1, 2, 'a'}
s.add(3) print(s) '''
{1, 2, 3, 'a'} ''' -
difference_update 去除原集合中重复的元素
pythoners = {'jason', 'nick', 'tank', 'sean'}
linuxers = {'nick', 'egon', 'kevin'}
pythoners.difference_update(linuxers) print(f"pythoners.difference_update(linuxers): {pythoners}") '''
pythoners.difference_update(linuxers): {'jason', 'sean', 'tank'}
''' -
isdisjoint 集合没有共同的部分返回True，否则返回False
pythoners = {'jason', 'nick', 'tank', 'sean'}
linuxers = {'nick', 'egon', 'kevin'}
pythoners.isdisjoint(linuxers) print(f"pythoners.isdisjoint(linuxers): {pythoners.isdisjoint(linuxers)}") '''
pythoners.isdisjoint(linuxers): False
''' -
remove 值不存在会报错
b = {1,2,3,4}
b.remove(4)
print(b) b.remove(5)
print(b) '''
{1, 2, 3} KeyError Traceback (most recent call last)
<ipython-input-84-af6d44ebcdf4> in <module>
1 a = {1,2,3}
2 b = {1,2,3,4}
----> 3 b.remove(5)
4 print(b) KeyError: 5 ''' -
discard # 不会报错
s = {1, 2, 'a'}
# s.remove(3) # 报错
s.discard(3) print(s) '''
{1, 2, 'a'} '''
-
-
多个值 or 一个值：多个值
有序 or 无序：无序
可变 or 不可变：可变
布尔类型
作用：一般用于判断，除了0/None/空/False自带布尔值为False,其他的数据类型自带布尔值为True
数据类型总结
定律：
id不变，值变，为可变类型。 id变，值变，为不可变类型
| 一个值 | 多个值 |
|---|---|
| 整型/浮点型/字符串 | 列表/元组/字典/集合 |
| 有序 | 无序 |
|---|---|
| 字符串/列表/元组 | 集合/字典 |
| 可变 | 不可变 |
|---|---|
| 列表/字典/集合 | 整型/浮点型/字符串 |