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 bbb".expandtabs()) # aaa bbb print("aaa bbb".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 %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 |