直接看文档是按顺序排列的有点乱，总结分类下，同时写一些备注，方便以后理解查阅
| 分类 | 函数 | 解释 | 例子 |
|---|---|---|---|
| 查询 | S.find(sub[, start[, end]]) -> int | Return the lowest index in S where substring sub is found, such that sub is contained within S[start:end]. Optional arguments start and end are interpreted as in slice notation. Return -1 on failure | |
| S.rfind(sub[, start[, end]]) -> int | Return the highest index in S where substring sub is found, such that sub is contained within S[start:end]. Optional arguments start and end are interpreted as in slice notation. Return -1 on failure. | s = "abab" s.rfind("ab") return 2 | |
| S.index(sub[, start[, end]]) -> int | Return the lowest index in S where substring sub is found, such that sub is contained within S[start:end]. Optional arguments start and end are interpreted as in slice notation. Raises ValueError when the substring is not found. | ||
| S.rindex(sub[, start[, end]]) -> int | Return the highest index in S where substring sub is found, such that sub is contained within S[start:end]. Optional arguments start and end are interpreted as in slice notation. Raises ValueError when the substring is not found. | ||
| 大小写 | S.upper() -> str | Return a copy of S converted to uppercase. | |
| S.lower() -> str | Return a copy of the string S converted to lowercase. | ||
| S.casefold() -> str | Return a version of S suitable for caseless comparisons. casefold()对于非英文的其他语言小写也有效 | ||
| S.swapcase() -> str | Return a copy of S with uppercase characters converted to lowercase and vice versa | hellO World ⬇ HELLo wORLD | |
| S.capitalize() -> str | Return a capitalized version of S, i.e. make the first character have upper case and the rest lower case. | hellO World ⬇ Hello world | |
| S.title() -> str | Return a titlecased version of S, i.e. words start with title case characters, all remaining cased characters have lower case. | hellO World ⬇ Hello World | |
| 对齐 | S.center(width[, fillchar]) -> str | Return S centered in a string of length width. Padding is done using the specified fill character (default is a space) | |
| S.ljust(width[, fillchar]) -> str | Return S left-justified in a Unicode string of length width. Padding is done using the specified fill character (default is a space). | ||
| S.rjust(width[, fillchar]) -> str | Return S right-justified in a string of length width. Padding is done using the specified fill character (default is a space). | ||
| S.zfill(width) -> str | Pad a numeric string S with zeros on the left, to fill a field of the specified width. The string S is never truncated （对字符串做改变的都不会改变原字符串）. | ||
| 分割 | S.split(sep=None, maxsplit=-1) -> list of strings | Return a list of the words in S, using sep as the delimiter string. If sep is not specified or is None, any whitespace string is a separator and empty strings are removed from the result. If maxsplit is given, at most maxsplit splits are done. | 例1 ‘a b c’.split() ⬇ [‘a’, ‘b’, ‘c’] 例2 ‘a b c’.split(’ ', 1) ⬇ [‘a’, ‘b c’] |
| S.rsplit(sep=None, maxsplit=-1) -> list of strings | Return a list of the words in S, using sep as the delimiter string, starting at the end of the string and working to the front. If maxsplit is given, at most maxsplit splits are done. If sep is not specified, any whitespace string is a separator. | 例1 ‘a b c’.split() ⬇ [‘a’, ‘b’, ‘c’] 例2 体现split和rsplit区别 ‘a b c’.split(’ ', 1) ⬇ [‘a b’, ’ c’] | |
| S.splitlines([keepends]) -> list of strings | Return a list of the lines in S, breaking at line boundaries Line breaks are not included in the resulting list unless keepends is given and true. | ||
| S.partition(sep) -> (head, sep, tail) | Search for the separator sep in S, and return the part before it, the separator itself, and the part after it. If the separator is not found, return S and two empty strings. （从头开始找，返回一个tuple） | ||
| S.rpartition(sep) -> (head, sep, tail) | Search for the separator sep in S, starting at the end of S, and return the part before it, the separator itself, and the part after it. If the separator is not found, return two empty strings and S. （从后往前找） | ||
| 合并 | S.join(iterable) -> str | Return a string which is the concatenation of the strings in the iterable. The separator between elements is S | d = 'abc' ", ".join(d) ⬇ 'a, b, c' d只要iterable 不一定是字符串 |
| 替换 | S.replace(old, new[, count]) -> str | Return a copy of S with all occurrences of substring old replaced by new. If the optional argument count is given, only the first count occurrences are replaced | |
| 判断 | S.isidentifier() -> bool | Return True if S is a valid identifier according to the language definition. Use keyword.iskeyword() to test for reserved identifiers such as “def” and “class”. 可用来判断变量名是否合法 | |
| S.isspace() -> bool | Return True if all characters in S are whitespace and there is at least one character in S, False otherwise. (whitespace: 空白、回车、换行和水平制表符) | ||
| S.isalpha() -> bool | Return True if all characters in S are alphabetic and there is at least one character in S, False otherwise | ||
| S.isdecimal() -> bool | Return True if there are only decimal characters in S, False otherwise. 判断是不是十进制数 True: 阿拉伯数字 False: 罗马数字，汉字数字 Error: byte数字（单字节）b'1' | ||
| S.isdigit() -> bool | Return True if all characters in S are digits and there is at least one character in S, False otherwise. True:阿拉伯数字，byte数字，罗马数字 False: 汉字数字 Error: 无 | ||
| S.isnumeric() -> bool | Return True if there are only numeric characters in S, False otherwise. True: 阿拉伯数字，罗马数字，汉字数字 False: 无 Error: byte数字（单字节） | ||
| S.isalnum() -> bool | Return True if all characters in S are alphanumeric and there is at least one character in S, False otherwise. | ||
| S.islower() -> bool | Return True if all cased characters in S are lowercase and there is at least one cased character in S, False otherwise. | ||
| S.isupper() -> bool | Return True if all cased characters in S are uppercase and there is at least one cased character in S, False otherwise. | ||
| S.istitle() -> bool | Return True if S is a titlecased string and there is at least one character in S, i.e. upper- and titlecase characters may only follow uncased characters and lowercase characters only cased ones. Return False otherwise. | ‘This Is A Title’ | |
| S.isprintable() -> bool | Return True if all characters in S are considered printable in repr() or S is empty, False otherwise. n就是不可打印 | ||
| 比较 | >, >=, <, <=, ==, != | 从第一个依次往下比较，比较oridinal value（原始值） | |
| ord(ch) | 将指定字符转为原始值 | ||
| chr(ch) | 将指定原始值转为字符 | ||
| 去除两端多余字符操作 | S.lstrip([chars]) -> str | Return a copy of the string S with leading whitespace removed. If chars is given and not None, remove characters in chars instead. | 例1 " myname".lstrip() ⬇ “myname” 例2 “myname”.lstrip(“my”) ⬇ “name” |
| S.rstrip([chars]) -> str | Return a copy of the string S with trailing whitespace removed. If chars is given and not None, remove characters in chars instead. | ||
| S.strip([chars]) -> str | Return a copy of the string S with leading and trailing whitespace removed. If chars is given and not None, remove characters in chars instead. | “!!!my!!!”.strip(“!”) ⬇ “my” | |
| 判断开头结尾字符串 | S.startswith(prefix[, start[, end]]) -> bool | Return True if S starts with the specified prefix, False otherwise. With optional start, test S beginning at that position. With optional end, stop comparing S at that position. prefix can also be a tuple of strings to try. | |
| S.endswith(suffix[, start[, end]]) -> bool | Return True if S ends with the specified suffix, False otherwise. With optional start, test S beginning at that position. With optional end, stop comparing S at that position. suffix can also be a tuple of strings to try. | ||
| 字符串计数 | S.count(sub[, start[, end]]) -> int | Return the number of non-overlapping occurrences of substring sub in string S[start:end]. Optional arguments start and end are interpreted as in slice notation. | |
| len(s) -> int | Return the number of items in a container | ||
| 编码 | S.encode(encoding='utf-8', errors='strict') -> bytes | Encode S using the codec registered for encoding. Default encoding is ‘utf-8’. Errors may be given to set a different error handling scheme. Default is ‘strict’ meaning that encoding errors raise a UnicodeEncodeError. Other possible values are ‘ignore’, ‘replace’ and ‘xmlcharrefreplace’ as well as any other name registered with codecs.register_error that can handle UnicodeEncodeErrors. | |
| 解码 | bytes.decode(self, /, encoding='utf-8', errors='strict') | Decode the bytes using the codec registered for encoding. encoding The encoding with which to decode the bytes. errors The error handling scheme to use for the handling of decoding errors. The default is ‘strict’ meaning that decoding errors raise a UnicodeDecodeError. Other possible values are ‘ignore’ and ‘replace’ as well as any other name registered with codecs.register_error that can handle UnicodeDecodeErrors. | |
| 翻译 | str.maketrans(x, y=None, z=None, /) | Return a translation table usable for str.translate(). If there is only one argument, it must be a dictionary mapping Unicode ordinals (integers) or characters to Unicode ordinals, strings or None. Character keys will be then converted to ordinals. If there are two arguments, they must be strings of equal length, and in the resulting dictionary, each character in x will be mapped to the character at the same position in y. If there is a third argument, it must be a string, whose characters will be mapped to None in the result. | table = str.maketrans(‘abc’, ‘123’, ‘none’) |
| S.translate(table) -> str | Return a copy of the string S in which each character has been mapped through the given translation table. The table must implement lookup/ indexing via __getitem__, for instance a dictionary or list, mapping Unicode ordinals to Unicode ordinals, strings, or None. If this operation raises LookupError, the character is left untouched. Characters mapped to None are deleted. | 结合上面的table ‘abcd’.translate(table) ⬇ ‘123d’ ‘none’.translate(table) ⬇ ‘’（none映射为空） | |
| 转换 | S.expandtabs(tabsize=8) -> str | Return a copy of S where all tab characters are expanded using spaces. If tabsize is not given, a tab size of 8 characters is assumed. | |
| S.format(*args, **kwargs) -> str | Return a formatted version of S, using substitutions from args and kwargs. The substitutions are identified by braces (‘{’ and ‘}’). | 例子见下面代码 | |
| S.format_map(mapping) -> str | Return a formatted version of S, using substitutions from mapping. The substitutions are identified by braces (‘{’ and ‘}’). | 例子见下面代码 |
- S.format_map(mapping) -> str
s = 'My name is {name}.'
name = 'xiaoming'
s.format_map(vars())
Out[]: 'My name is xiaoming.'
# vars()也能作用在类实例上
class Name:
def __init__(self, name, n):
self.name = name
ppl = Name('xiaoming')
s.format_map(vars(ppl))
Out[]: 'My name is xiaoming.'
- S.format(*args, **kwargs) -> str
'Hello {}'.format('Word')===>Hello Word
-------------------------------------------------
'你喜欢{2}吗？难道你喜欢{1}，我猜你喜欢{0}'.format('java','c++','python')
===>你喜欢python吗？难道你喜欢c++，我猜你喜欢java
---------------------------------------------------
name='james'
age=12
'我的名字是{}，年龄是{}'.format(name,age)
===>我的名字是james，年龄是12
-----------------------------------------------------
'我的名字是{name}，年龄{age}'.format(name='bob',age='30')
===>>我的名字是bob，年龄30
----------------------------------------------------
coord = {'latitude': '37.24N', 'longitude': '-115.81W'}
'Coordinates: {latitude}, {longitude}'.format(**coord)
===>Coordinates: 37.24N, -115.81W
-----------------------------------------------------
'{}-{}-{}'.format(*'abc')==>>a-b-c
-------------------------------------------------
'{:*>10}'.format('love you')
#右对齐默认用空格填充，这个例子设置星号填充
===>>**love you
-------------------------------------------------------
'{:*^30}'.format('centered')
#居中对齐，默认空格填充，这个例子用性星号填充
===>>>***********centered***********
------------------------------------------------------
'{:*<10}'.format('love you')
#左对齐默认用空格填充，这个例子设置星号填充
=====>>>>love you**
-------------------------------------------------------
'{:.4f}; {:.3f};{:f}'.format(3.14, -3.14,3)
#浮点数保留指定位数小数，未指定则默认六位
===>>>3.1400; -3.140;3.000000
--------------------------------------------------------
"int: {0:d}; hex: {0:x}; oct: {0:o}; bin: {0:b}".format(42)
#十进制，16进制，八进制，2进制转换
===>>>int: 42; hex: 2a; oct: 52; bin: 101010
-------------------------------------------------------
"int: {0:d}; hex: {0:#x}; oct: {0:#o}; bin: {0:#b}".format(42)
#加上#好之后
====>>>int: 42; hex: 0x2a; oct: 0o52; bin: 0b101010
--------------------------------------------------------
'{:,}'.format(1234567890)#用逗号作为千位分割符
===》》》1,234,567,890
------------------------------------------------
points=19
total=22
'{:.2%}'.format(19/22)#表示百分数==>>86.36%
-----------------------------------------------------
import datetime
d = datetime.datetime(2010, 7, 4, 12, 15, 58)
st='{:%Y-%m-%d %H:%M:%S}'.format(d)
#格式化时间
==>>>2010-07-04 12:15:58
----------------------------------------------------
octets = [192, 168, 0, 1]
'{:02X}{:02X}{:02X}{:02X}'.format(*octets)
===>>>C0A80001
