python基础之一——数据类型和内存管理

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 |
capitalize(...)
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S.capitalize() -> str
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Return a capitalized version of S, i.e. make the first character
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have upper case and the rest lower case.
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casefold(...)
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S.casefold() -> str
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Return a version of S suitable for caseless comparisons.
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center(...)
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S.center(width[, fillchar]) -> str
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Return S centered in a string of length width. Padding is
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done using the specified fill character (default is a space)
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count(...)
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S.count(sub[, start[, end]]) -> int
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Return the number of non-overlapping occurrences of substring sub in
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string S[start:end].
Optional arguments start and end are
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interpreted as in slice notation.
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encode(...)
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S.encode(encoding='utf-8', errors='strict') -> bytes
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Encode S using the codec registered for encoding. Default encoding
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is 'utf-8'. errors may be given to set a different error
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handling scheme. Default is 'strict' meaning that encoding errors raise
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a UnicodeEncodeError. Other possible values are 'ignore', 'replace' and
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'xmlcharrefreplace' as well as any other name registered with
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codecs.register_error that can handle UnicodeEncodeErrors.
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endswith(...)
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S.endswith(suffix[, start[, end]]) -> bool
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Return True if S ends with the specified suffix, False otherwise.
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With optional start, test S beginning at that position.
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With optional end, stop comparing S at that position.
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suffix can also be a tuple of strings to try.
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expandtabs(...)
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S.expandtabs(tabsize=8) -> str
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Return a copy of S where all tab characters are expanded using spaces.
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If tabsize is not given, a tab size of 8 characters is assumed.
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find(...)
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S.find(sub[, start[, end]]) -> int
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Return the lowest index in S where substring sub is found,
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such that sub is contained within S[start:end].
Optional
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arguments start and end are interpreted as in slice notation.
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Return -1 on failure.
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format(...)
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S.format(*args, **kwargs) -> str
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Return a formatted version of S, using substitutions from args and kwargs.
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The substitutions are identified by braces ('{' and '}').
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format_map(...)
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S.format_map(mapping) -> str
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Return a formatted version of S, using substitutions from mapping.
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The substitutions are identified by braces ('{' and '}').
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index(...)
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S.index(sub[, start[, end]]) -> int
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Like S.find() but raise ValueError when the substring is not found.
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isalnum(...)
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S.isalnum() -> bool
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Return True if all characters in S are alphanumeric
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and there is at least one character in S, False otherwise.
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isalpha(...)
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S.isalpha() -> bool
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Return True if all characters in S are alphabetic
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and there is at least one character in S, False otherwise.
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isdecimal(...)
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S.isdecimal() -> bool
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Return True if there are only decimal characters in S,
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False otherwise.
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isdigit(...)
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S.isdigit() -> bool
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Return True if all characters in S are digits
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and there is at least one character in S, False otherwise.
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isidentifier(...)
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S.isidentifier() -> bool
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Return True if S is a valid identifier according
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to the language definition.
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Use keyword.iskeyword() to test for reserved identifiers
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such as "def" and "class".
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islower(...)
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S.islower() -> bool
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Return True if all cased characters in S are lowercase and there is
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at least one cased character in S, False otherwise.
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isnumeric(...)
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S.isnumeric() -> bool
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Return True if there are only numeric characters in S,
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False otherwise.
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isprintable(...)
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S.isprintable() -> bool
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Return True if all characters in S are considered
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printable in repr() or S is empty, False otherwise.
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isspace(...)
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S.isspace() -> bool
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Return True if all characters in S are whitespace
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and there is at least one character in S, False otherwise.
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istitle(...)
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S.istitle() -> bool
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Return True if S is a titlecased string and there is at least one
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character in S, i.e. upper- and titlecase characters may only
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follow uncased characters and lowercase characters only cased ones.
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Return False otherwise.
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isupper(...)
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S.isupper() -> bool
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Return True if all cased characters in S are uppercase and there is
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at least one cased character in S, False otherwise.
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join(...)
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S.join(iterable) -> str
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Return a string which is the concatenation of the strings in the
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iterable.
The separator between elements is S.
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ljust(...)
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S.ljust(width[, fillchar]) -> str
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Return S left-justified in a Unicode string of length width. Padding is
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done using the specified fill character (default is a space).
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lower(...)
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S.lower() -> str
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Return a copy of the string S converted to lowercase.
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lstrip(...)
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S.lstrip([chars]) -> str
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Return a copy of the string S with leading whitespace removed.
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If chars is given and not None, remove characters in chars instead.
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partition(...)
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S.partition(sep) -> (head, sep, tail)
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Search for the separator sep in S, and return the part before it,
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the separator itself, and the part after it.
If the separator is not
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found, return S and two empty strings.
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replace(...)
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S.replace(old, new[, count]) -> str
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Return a copy of S with all occurrences of substring
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old replaced by new.
If the optional argument count is
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given, only the first count occurrences are replaced.
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rfind(...)
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S.rfind(sub[, start[, end]]) -> int
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Return the highest index in S where substring sub is found,
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such that sub is contained within S[start:end].
Optional
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arguments start and end are interpreted as in slice notation.
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Return -1 on failure.
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rindex(...)
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S.rindex(sub[, start[, end]]) -> int
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Like S.rfind() but raise ValueError when the substring is not found.
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rjust(...)
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S.rjust(width[, fillchar]) -> str
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Return S right-justified in a string of length width. Padding is
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done using the specified fill character (default is a space).
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rpartition(...)
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S.rpartition(sep) -> (head, sep, tail)
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Search for the separator sep in S, starting at the end of S, and return
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the part before it, the separator itself, and the part after it.
If the
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separator is not found, return two empty strings and S.
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rsplit(...)
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S.rsplit(sep=None, maxsplit=-1) -> list of strings
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Return a list of the words in S, using sep as the
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delimiter string, starting at the end of the string and
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working to the front.
If maxsplit is given, at most maxsplit
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splits are done. If sep is not specified, any whitespace string
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is a separator.
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rstrip(...)
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S.rstrip([chars]) -> str
|
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Return a copy of the string S with trailing whitespace removed.
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If chars is given and not None, remove characters in chars instead.
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split(...)
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S.split(sep=None, maxsplit=-1) -> list of strings
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Return a list of the words in S, using sep as the
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delimiter string.
If maxsplit is given, at most maxsplit
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splits are done. If sep is not specified or is None, any
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whitespace string is a separator and empty strings are
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removed from the result.
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splitlines(...)
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S.splitlines([keepends]) -> list of strings
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Return a list of the lines in S, breaking at line boundaries.
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Line breaks are not included in the resulting list unless keepends
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is given and true.
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startswith(...)
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S.startswith(prefix[, start[, end]]) -> bool
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Return True if S starts with the specified prefix, False otherwise.
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With optional start, test S beginning at that position.
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With optional end, stop comparing S at that position.
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prefix can also be a tuple of strings to try.
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strip(...)
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S.strip([chars]) -> str
|
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Return a copy of the string S with leading and trailing
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whitespace removed.
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If chars is given and not None, remove characters in chars instead.
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swapcase(...)
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S.swapcase() -> str
|
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Return a copy of S with uppercase characters converted to lowercase
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and vice versa.
|
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title(...)
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S.title() -> str
|
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Return a titlecased version of S, i.e. words start with title case
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characters, all remaining cased characters have lower case.
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translate(...)
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S.translate(table) -> str
|
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Return a copy of the string S in which each character has been mapped
|
through the given translation table. The table must implement
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lookup/indexing via __getitem__, for instance a dictionary or list,
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mapping Unicode ordinals to Unicode ordinals, strings, or None. If
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this operation raises LookupError, the character is left untouched.
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Characters mapped to None are deleted.
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upper(...)
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S.upper() -> str
|
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Return a copy of S converted to uppercase.
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zfill(...)
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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.

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>>> s="Simple is better than complex."
>>> "{}".format(s)
#一般格式
'Simple is better than complex.'
>>> "{:40}".format(s)
#最小40个字符
'Simple is better than complex.
'
>>> "{:>40}".format(s)
'
Simple is better than complex.'
>>> "{:^40}".format(s)
'
Simple is better than complex.
'
>>> "{:-^40}".format(s)
'-----Simple is better than complex.-----'
>>> "{:.<40}".format(s)
#指定了一个填充字符，就必须同时指定对齐字符。
'Simple is better than complex...........'
>>> "{:.10}".format(s)
#最长10个字符
'Simple is '
>>> "{:#=40}".format("-34546")
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: '=' alignment not allowed in string format specifier
>>> "{:#=40}".format(34546)
'###################################34546'
>>> "{: }".format(12345)
' 12345'
>>> "{:*^ 15}".format(1234)
'***** 1234*****'
>>> "{:*^-15}".format(1234)
'*****1234******'
>>> "{:*^-15}".format(-1234)
'*****-1234*****'
>>> "{:*^+15}".format(1234)
'*****+1234*****'
>>> "{:*^#15x}".format(1234)
'*****0x4d2*****'
>>> "{:*^#15b}".format(34)
'***0b100010****'

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 |
append(...)
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L.append(object) -> None -- append object to end
|
|
clear(...)
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L.clear() -> None -- remove all items from L
|
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copy(...)
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L.copy() -> list -- a shallow copy of L
|
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count(...)
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L.count(value) -> integer -- return number of occurrences of value
|
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extend(...)
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L.extend(iterable) -> None -- extend list by appending elements from the iterable
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index(...)
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L.index(value, [start, [stop]]) -> integer -- return first index of value.
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Raises ValueError if the value is not present.
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insert(...)
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L.insert(index, object) -- insert object before index
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pop(...)
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L.pop([index]) -> item -- remove and return item at index (default last).
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Raises IndexError if list is empty or index is out of range.
|
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remove(...)
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L.remove(value) -> None -- remove first occurrence of value.
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Raises ValueError if the value is not present.
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reverse(...)
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L.reverse() -- reverse *IN PLACE*
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sort(...)
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L.sort(key=None, reverse=False) -> None -- stable sort *IN PLACE*

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count(...)
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T.count(value) -> integer -- return number of occurrences of value
|
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index(...)
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T.index(value, [start, [stop]]) -> integer -- return first index of value.
|
Raises ValueError if the value is not present.

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clear(...)
|
D.clear() -> None.
Remove all items from D.
|
|
copy(...)
|
D.copy() -> a shallow copy of D
|
|
fromkeys(iterable, value=None, /) from builtins.type
|
Returns a new dict with keys from iterable and values equal to value.
|
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get(...)
|
D.get(k[,d]) -> D[k] if k in D, else d.
d defaults to None.
|
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items(...)
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D.items() -> a set-like object providing a view on D's items
|
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keys(...)
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D.keys() -> a set-like object providing a view on D's keys
|
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pop(...)
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D.pop(k[,d]) -> v, remove specified key and return the corresponding value.
|
If key is not found, d is returned if given, otherwise KeyError is raised
|
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popitem(...)
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D.popitem() -> (k, v), remove and return some (key, value) pair as a
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2-tuple; but raise KeyError if D is empty.
|
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setdefault(...)
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D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D
|
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update(...)
|
D.update([E, ]**F) -> None.
Update D from dict/iterable E and F.
|
If E is present and has a .keys() method, then does:
for k in E: D[k] = E[k]
|
If E is present and lacks a .keys() method, then does:
for k, v in E: D[k] = v
|
In either case, this is followed by: for k in F:
D[k] = F[k]
|
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values(...)
|
D.values() -> an object providing a view on D's values

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#固定缓冲区
>>> a=-5
>>> b=-5
>>> id(-5)
505370256
>>> id(a)
505370256
>>> id(b)
505370256
>>> c=256
>>> d=256
>>> print(id(c),id(d),id(256))
505374432 505374432 505374432
>>> e=257
>>> f=257
>>> print(id(e),id(f),id(257))
54155072 54155104 54155120
#可重复利用缓冲区（不同电脑，不同编译器，有可能不一样）
>>> id(10000)
2660846579440
>>> id(1000010)
2660846579440
>>> id(1000)
2660846579440
>>> id(1233)
2660846579440

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>>> a=[1,2,3,[1,2]]
>>> b=a
>>> print(id(a),id(b))
56164304 56164304
>>> b[1]="hello"
>>> a
[1, 'hello', 3, [1, 2]]
>>> b
[1, 'hello', 3, [1, 2]]
>>> b[3].append(9)
>>> a
[1, 'hello', 3, [1, 2, 9]]
>>> b
[1, 'hello', 3, [1, 2, 9]]

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>>> a=[1234,"123",[1,2,899]]
>>> b=copy.copy(a)
>>> c=copy.deepcopy(a)
>>> print(id(a),id(b),id(c))
52773272 52624680 52625320
#这是三个不同的对象
>>> print(id(a[0]),id(b[0]),id(c[0]))
52320176 52320176 52320176
#对于简单数据类型的处理是一样的
>>> print(id(a[2]),id(b[2]),id(c[2]))
52774512 52774512 52625160
# 注意啦，区别就在这