Python高手之路【二】python基本数据类型

最新推荐文章于 2025-10-11 10:03:20 发布

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#python #开发语言

本文详细介绍了Python的几种基本数据类型，包括数字（整型、长整型和浮点型）、字符串、列表、元组和字典。讨论了每种类型的特性和常用操作，如字符串的连接、截取、替换、比较、查找、分割等；列表的创建、访问、添加、删除元素以及遍历方法；元组的创建、连接和删除；字典的访问、更新、删除元素以及遍历方法。文章适合Python初学者深入理解数据类型及其操作。

一：数字 int

int(整型)：

　　在32位机器上，整数的位数为32位，取值范围为-2**31～2**31-1，即-2147483648～2147483647
　　在64位系统上，整数的位数为64位，取值范围为-2**63～2**63-1，即-9223372036854775808～9223372036854775807

long（长整型）：

　　跟C语言不同，Python的长整数没有指定位宽，即：Python没有限制长整数数值的大小，但实际上由于机器内存有限，我们使用的长整数数值不可能无限大

　　注意：自从python2.2起，如果整数发生溢出，python会自动将整数数据转换为长整数，所以如今在长整数数据后面不加字母L也不会导致严重后果了

float（浮点型）：

　　浮点数用来处理实数，即带有小数的数字，类似于C语言中的double类型，占8个字节（64位），其中52位表示底，11位表示指数，剩下一位表示符号

class int(object):
    """
    int(x=0) -> int or long
    int(x, base=10) -> int or long
 
    Convert a number or string to an integer, or return 0 if no arguments
    are given.  If x is floating point, the conversion truncates towards zero.
    If x is outside the integer range, the function returns a long instead.
 
    If x is not a number or if base is given, then x must be a string or
    Unicode object representing an integer literal in the given base.  The
    literal can be preceded by '+' or '-' and be surrounded by whitespace.
    The base defaults to 10.  Valid bases are 0 and 2-36.  Base 0 means to
    interpret the base from the string as an integer literal.
    >>> int('0b100', base=0)
    """
    def bit_length(self):
        """ 返回表示该数字的时占用的最少位数 """
        """
        int.bit_length() -> int
 
        Number of bits necessary to represent self in binary.
        >>> bin(37)
        '0b100101'
        >>> (37).bit_length()
        """
        return 0
 
    def conjugate(self, *args, **kwargs): # real signature unknown
        """ 返回该复数的共轭复数 """
        """ Returns self, the complex conjugate of any int. """
        pass
 
    def __abs__(self):
        """ 返回绝对值 """
        """ x.__abs__() <==> abs(x) """
        pass
 
    def __add__(self, y):
        """ x.__add__(y) <==> x+y """
        pass
 
    def __and__(self, y):
        """ x.__and__(y) <==> x&y """
        pass
 
    def __cmp__(self, y):
        """ 比较两个数大小 """
        """ x.__cmp__(y) <==> cmp(x,y) """
        pass
 
    def __coerce__(self, y):
        """ 强制生成一个元组 """
        """ x.__coerce__(y) <==> coerce(x, y) """
        pass
 
    def __divmod__(self, y):
        """ 相除，得到商和余数组成的元组 """
        """ x.__divmod__(y) <==> divmod(x, y) """
        pass
 
    def __div__(self, y):
        """ x.__div__(y) <==> x/y """
        pass
 
    def __float__(self):
        """ 转换为浮点类型 """
        """ x.__float__() <==> float(x) """
        pass
 
    def __floordiv__(self, y):
        """ x.__floordiv__(y) <==> x//y """
        pass
 
    def __format__(self, *args, **kwargs): # real signature unknown
        pass
 
    def __getattribute__(self, name):
        """ x.__getattribute__('name') <==> x.name """
        pass
 
    def __getnewargs__(self, *args, **kwargs): # real signature unknown
        """ 内部调用 __new__方法或创建对象时传入参数使用 """
        pass
 
    def __hash__(self):
        """如果对象object为哈希表类型，返回对象object的哈希值。哈希值为整数。在字典查找中，哈希值用于快速比较字典的键。两个数值如果相等，则哈希值也相等。"""
        """ x.__hash__() <==> hash(x) """
        pass
 
    def __hex__(self):
        """ 返回当前数的 十六进制 表示 """
        """ x.__hex__() <==> hex(x) """
        pass
 
    def __index__(self):
        """ 用于切片，数字无意义 """
        """ x[y:z] <==> x[y.__index__():z.__index__()] """
        pass
 
    def __init__(self, x, base=10): # known special case of int.__init__
        """ 构造方法，执行 x = 123 或 x = int(10) 时，自动调用，暂时忽略 """
        """
        int(x=0) -> int or long
        int(x, base=10) -> int or long
 
        Convert a number or string to an integer, or return 0 if no arguments
        are given.  If x is floating point, the conversion truncates towards zero.
        If x is outside the integer range, the function returns a long instead.
 
        If x is not a number or if base is given, then x must be a string or
        Unicode object representing an integer literal in the given base.  The
        literal can be preceded by '+' or '-' and be surrounded by whitespace.
        The base defaults to 10.  Valid bases are 0 and 2-36.  Base 0 means to
        interpret the base from the string as an integer literal.
        >>> int('0b100', base=0)
        # (copied from class doc)
        """
        pass
 
    def __int__(self):
        """ 转换为整数 """
        """ x.__int__() <==> int(x) """
        pass
 
    def __invert__(self):
        """ x.__invert__() <==> ~x """
        pass
 
    def __long__(self):
        """ 转换为长整数 """
        """ x.__long__() <==> long(x) """
        pass
 
    def __lshift__(self, y):
        """ x.__lshift__(y) <==> x<<y """
        pass
 
    def __mod__(self, y):
        """ x.__mod__(y) <==> x%y """
        pass
 
    def __mul__(self, y):
        """ x.__mul__(y) <==> x*y """
        pass
 
    def __neg__(self):
        """ x.__neg__() <==> -x """
        pass
 
    @staticmethod # known case of __new__
    def __new__(S, *more):
        """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
        pass
 
    def __nonzero__(self):
        """ x.__nonzero__() <==> x != 0 """
        pass
 
    def __oct__(self):
        """ 返回改值的 八进制 表示 """
        """ x.__oct__() <==> oct(x) """
        pass
 
    def __or__(self, y):
        """ x.__or__(y) <==> x|y """
        pass
 
    def __pos__(self):
        """ x.__pos__() <==> +x """
        pass
 
    def __pow__(self, y, z=None):
        """ 幂，次方 """
        """ x.__pow__(y[, z]) <==> pow(x, y[, z]) """
        pass
 
    def __radd__(self, y):
        """ x.__radd__(y) <==> y+x """
        pass
 
    def __rand__(self, y):
        """ x.__rand__(y) <==> y&x """
        pass
 
    def __rdivmod__(self, y):
        """ x.__rdivmod__(y) <==> divmod(y, x) """
        pass
 
    def __rdiv__(self, y):
        """ x.__rdiv__(y) <==> y/x """
        pass
 
    def __repr__(self):
        """转化为解释器可读取的形式 """
        """ x.__repr__() <==> repr(x) """
        pass
 
    def __str__(self):
        """转换为人阅读的形式，如果没有适于人阅读的解释形式的话，则返回解释器课阅读的形式"""
        """ x.__str__() <==> str(x) """
        pass
 
    def __rfloordiv__(self, y):
        """ x.__rfloordiv__(y) <==> y//x """
        pass
 
    def __rlshift__(self, y):
        """ x.__rlshift__(y) <==> y<<x """
        pass
 
    def __rmod__(self, y):
        """ x.__rmod__(y) <==> y%x """
        pass
 
    def __rmul__(self, y):
        """ x.__rmul__(y) <==> y*x """
        pass
 
    def __ror__(self, y):
        """ x.__ror__(y) <==> y|x """
        pass
 
    def __rpow__(self, x, z=None):
        """ y.__rpow__(x[, z]) <==> pow(x, y[, z]) """
        pass
 
    def __rrshift__(self, y):
        """ x.__rrshift__(y) <==> y>>x """
        pass
 
    def __rshift__(self, y):
        """ x.__rshift__(y) <==> x>>y """
        pass
 
    def __rsub__(self, y):
        """ x.__rsub__(y) <==> y-x """
        pass
 
    def __rtruediv__(self, y):
        """ x.__rtruediv__(y) <==> y/x """
        pass
 
    def __rxor__(self, y):
        """ x.__rxor__(y) <==> y^x """
        pass
 
    def __sub__(self, y):
        """ x.__sub__(y) <==> x-y """
        pass
 
    def __truediv__(self, y):
        """ x.__truediv__(y) <==> x/y """
        pass
 
    def __trunc__(self, *args, **kwargs):
        """ 返回数值被截取为整形的值，在整形中无意义 """
        pass
 
    def __xor__(self, y):
        """ x.__xor__(y) <==> x^y """
        pass
 
    denominator = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 分母 = 1 """
    """the denominator of a rational number in lowest terms"""
 
    imag = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 虚数，无意义 """
    """the imaginary part of a complex number"""
 
    numerator = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 分子 = 数字大小 """
    """the numerator of a rational number in lowest terms"""
 
    real = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 实属，无意义 """
    """the real part of a complex number"""
 
int

int

二：字符串 str

class str(basestring):
    """
    str(object='') -> string
 
    Return a nice string representation of the object.
    If the argument is a string, the return value is the same object.
    """
    def capitalize(self):
        """ 首字母变大写 """
        """
        S.capitalize() -> string
 
        Return a copy of the string S with only its first character
        capitalized.
        """
        return ""
 
    def center(self, width, fillchar=None):
        """ 内容居中，width：总长度；fillchar：空白处填充内容，默认无 """
        """
        S.center(width[, fillchar]) -> string
 
        Return S centered in a string of length width. Padding is
        done using the specified fill character (default is a space)
        """
        return ""
 
    def count(self, sub, start=None, end=None):
        """ 子序列个数 """
        """
        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.
        """
        return 0
 
    def decode(self, encoding=None, errors=None):
        """ 解码 """
        """
        S.decode([encoding[,errors]]) -> object
 
        Decodes S using the codec registered for encoding. encoding defaults
        to the default encoding. errors may be given to set a different error
        handling scheme. Default is 'strict' meaning that encoding errors raise
        a UnicodeDecodeError. Other possible values are 'ignore' and 'replace'
        as well as any other name registered with codecs.register_error that is
        able to handle UnicodeDecodeErrors.
        """
        return object()
 
    def encode(self, encoding=None, errors=None):
        """ 编码，针对unicode """
        """
        S.encode([encoding[,errors]]) -> object
 
        Encodes S using the codec registered for encoding. encoding defaults
        to the default encoding. 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 is able to handle UnicodeEncodeErrors.
        """
        return object()
 
    def endswith(self, suffix, start=None, end=None):
        """ 是否以 xxx 结束 """
        """
        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.
        """
        return False
 
    def expandtabs(self, tabsize=None):
        """ 将tab转换成空格，默认一个tab转换成8个空格 """
        """
        S.expandtabs([tabsize]) -> string
 
        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.
        """
        return ""
 
    def find(self, sub, start=None, end=None):
        """ 寻找子序列位置，如果没找到，返回 -1 """
        """
        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.
        """
        return 0
 
    def format(*args, **kwargs): # known special case of str.format
        """ 字符串格式化，动态参数，将函数式编程时细说 """
        """
        S.format(*args, **kwargs) -> string
 
        Return a formatted version of S, using substitutions from args and kwargs.
        The substitutions are identified by braces ('{' and '}').
        """
        pass
 
    def index(self, sub, start=None, end=None):
        """ 子序列位置，如果没找到，报错 """
        S.index(sub [,start [,end]]) -> int
 
        Like S.find() but raise ValueError when the substring is not found.
        """
        return 0
 
    def isalnum(self):
        """ 是否是字母和数字 """
        """
        S.isalnum() -> bool
 
        Return True if all characters in S are alphanumeric
        and there is at least one character in S, False otherwise.
        """
        return False
 
    def isalpha(self):
        """ 是否是字母 """
        """
        S.isalpha() -> bool
 
        Return True if all characters in S are alphabetic
        and there is at least one character in S, False otherwise.
        """
        return False
 
    def isdigit(self):
        """ 是否是数字 """
        """
        S.isdigit() -> bool
 
        Return True if all characters in S are digits
        and there is at least one character in S, False otherwise.
        """
        return False
 
    def islower(self):
        """ 是否小写 """
        """
        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.
        """
        return False
 
    def isspace(self):
        """
        S.isspace() -> bool
 
        Return True if all characters in S are whitespace
        and there is at least one character in S, False otherwise.
        """
        return False
 
    def istitle(self):
        """
        S.istitle() -> bool
 
        Return True if S is a titlecased string and there is at least one
        character in S, i.e. uppercase characters may only follow uncased
        characters and lowercase characters only cased ones. Return False
        otherwise.
        """
        return False
 
    def isupper(self):
        """
        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.
        """
        return False
 
    def join(self, iterable):
        """ 连接 """
        """
        S.join(iterable) -> string
 
        Return a string which is the concatenation of the strings in the
        iterable.  The separator between elements is S.
        """
        return ""
 
    def ljust(self, width, fillchar=None):
        """ 内容左对齐，右侧填充 """
        """
        S.ljust(width[, fillchar]) -> string
 
        Return S left-justified in a string of length width. Padding is
        done using the specified fill character (default is a space).
        """
        return ""
 
    def lower(self):
        """ 变小写 """
        """
        S.lower() -> string
 
        Return a copy of the string S converted to lowercase.
        """
        return ""
 
    def lstrip(self, chars=None):
        """ 移除左侧空白 """
        """
        S.lstrip([chars]) -> string or unicode
 
        Return a copy of the string S with leading whitespace removed.
        If chars is given and not None, remove characters in chars instead.
        If chars is unicode, S will be converted to unicode before stripping
        """
        return ""
 
    def partition(self, sep):
        """ 分割，前，中，后三部分 """
        """
        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.
        """
        pass
 
    def replace(self, old, new, count=None):
        """ 替换 """
        """
        S.replace(old, new[, count]) -> string
 
        Return a copy of string S with all occurrences of substring
        old replaced by new.  If the optional argument count is
        given, only the first count occurrences are replaced.
        """
        return ""
 
    def rfind(self, sub, start=None, end=None):
        """
        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.
        """
        return 0
 
    def rindex(self, sub, start=None, end=None):
        """
        S.rindex(sub [,start [,end]]) -> int
 
        Like S.rfind() but raise ValueError when the substring is not found.
        """
        return 0
 
    def rjust(self, width, fillchar=None):
        """
        S.rjust(width[, fillchar]) -> string
 
        Return S right-justified in a string of length width. Padding is
        done using the specified fill character (default is a space)
        """
        return ""
 
    def rpartition(self, sep):
        """
        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.
        """
        pass
 
    def rsplit(self, sep=None, maxsplit=None):
        """
        S.rsplit([sep [,maxsplit]]) -> list of strings
 
        Return a list of the words in the string 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 or is None, any whitespace string
        is a separator.
        """
        return []
 
    def rstrip(self, chars=None):
        """
        S.rstrip([chars]) -> string or unicode
 
        Return a copy of the string S with trailing whitespace removed.
        If chars is given and not None, remove characters in chars instead.
        If chars is unicode, S will be converted to unicode before stripping
        """
        return ""
 
    def split(self, sep=None, maxsplit=None):
        """ 分割， maxsplit最多分割几次 """
        """
        S.split([sep [,maxsplit]]) -> list of strings
 
        Return a list of the words in the string S, using sep as the
        delimiter string.  If maxsplit is given, at most maxsplit
        splits are done. If sep is not specified or is None, any
        whitespace string is a separator and empty strings are removed
        from the result.
        """
        return []
 
    def splitlines(self, keepends=False):
        """ 根据换行分割 """
        """
        S.splitlines(keepends=False) -> 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.
        """
        return []
 
    def startswith(self, prefix, start=None, end=None):
        """ 是否起始 """
        """
        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.
        """
        return False
 
    def strip(self, chars=None):
        """ 移除两段空白 """
        """
        S.strip([chars]) -> string or unicode
 
        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.
        If chars is unicode, S will be converted to unicode before stripping
        """
        return ""
 
    def swapcase(self):
        """ 大写变小写，小写变大写 """
        """
        S.swapcase() -> string
 
        Return a copy of the string S with uppercase characters
        converted to lowercase and vice versa.
        """
        return ""
 
    def title(self):
        """
        S.title() -> string
 
        Return a titlecased version of S, i.e. words start with uppercase
        characters, all remaining cased characters have lowercase.
        """
        return ""
 
    def translate(self, table, deletechars=None):
        """
        转换，需要先做一个对应表，最后一个表示删除字符集合
        intab = "aeiou"
        outtab = ""
        trantab = maketrans(intab, outtab)
        str = "this is string example....wow!!!"
        print str.translate(trantab, 'xm')
        """
 
        """
        S.translate(table [,deletechars]) -> string
 
        Return a copy of the string S, where all characters occurring
        in the optional argument deletechars are removed, and the
        remaining characters have been mapped through the given
        translation table, which must be a string of length 256 or None.
        If the table argument is None, no translation is applied and
        the operation simply removes the characters in deletechars.
        """
        return ""
 
    def upper(self):
        """
        S.upper() -> string
 
        Return a copy of the string S converted to uppercase.
        """
        return ""
 
    def zfill(self, width):
        """方法返回指定长度的字符串，原字符串右对齐，前面填充0。"""
        """
        S.zfill(width) -> string
 
        Pad a numeric string S with zeros on the left, to fill a field
        of the specified width.  The string S is never truncated.
        """
        return ""
 
    def _formatter_field_name_split(self, *args, **kwargs): # real signature unknown
        pass
 
    def _formatter_parser(self, *args, **kwargs): # real signature unknown
        pass
 
    def __add__(self, y):
        """ x.__add__(y) <==> x+y """
        pass
 
    def __contains__(self, y):
        """ x.__contains__(y) <==> y in x """
        pass
 
    def __eq__(self, y):
        """ x.__eq__(y) <==> x==y """
        pass
 
    def __format__(self, format_spec):
        """
        S.__format__(format_spec) -> string
 
        Return a formatted version of S as described by format_spec.
        """
        return ""
 
    def __getattribute__(self, name):
        """ x.__getattribute__('name') <==> x.name """
        pass
 
    def __getitem__(self, y):
        """ x.__getitem__(y) <==> x[y] """
        pass
 
    def __getnewargs__(self, *args, **kwargs): # real signature unknown
        pass
 
    def __getslice__(self, i, j):
        """
        x.__getslice__(i, j) <==> x[i:j]
 
                   Use of negative indices is not supported.
        """
        pass
 
    def __ge__(self, y):
        """ x.__ge__(y) <==> x>=y """
        pass
 
    def __gt__(self, y):
        """ x.__gt__(y) <==> x>y """
        pass
 
    def __hash__(self):
        """ x.__hash__() <==> hash(x) """
        pass
 
    def __init__(self, string=''): # known special case of str.__init__
        """
        str(object='') -> string
 
        Return a nice string representation of the object.
        If the argument is a string, the return value is the same object.
        # (copied from class doc)
        """
        pass
 
    def __len__(self):
        """ x.__len__() <==> len(x) """
        pass
 
    def __le__(self, y):
        """ x.__le__(y) <==> x<=y """
        pass
 
    def __lt__(self, y):
        """ x.__lt__(y) <==> x<y """
        pass
 
    def __mod__(self, y):
        """ x.__mod__(y) <==> x%y """
        pass
 
    def __mul__(self, n):
        """ x.__mul__(n) <==> x*n """
        pass
 
    @staticmethod # known case of __new__
    def __new__(S, *more):
        """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
        pass
 
    def __ne__(self, y):
        """ x.__ne__(y) <==> x!=y """
        pass
 
    def __repr__(self):
        """ x.__repr__() <==> repr(x) """
        pass
 
    def __rmod__(self, y):
        """ x.__rmod__(y) <==> y%x """
        pass
 
    def __rmul__(self, n):
        """ x.__rmul__(n) <==> n*x """
        pass
 
    def __sizeof__(self):
        """ S.__sizeof__() -> size of S in memory, in bytes """
        pass
 
    def __str__(self):
        """ x.__str__() <==> str(x) """
        pass
 
str

str

字符串是 Python 中最常用的数据类型。我们可以使用引号，双引号，或三引号来创建字符串。

a = 'poe'
b = "bruce"
c = """Jacky Chen"""

1：字符串连接

方法一：join方法

a = ['a','b','c','d']
 content = ''
 content = ' '.join(a)
 print(content)

方法二：用字符串的替换占位符替换

 a = ['a','b','c','d']
 content = ''
 content = '%s%s%s%s' % tuple(a)
 print(content)

方法三：for循环

 a = ['a','b','c','d']
 content = ''
 for i in a:
     content += i
 print(content)

注意：方法三效率低，不推荐使用！

原因：在循环连接字符串的时候，他每次连接一次，就要重新开辟空间，然后把字符串连接起来，再放入新的空间，再一次循环，又要开辟新的空间，把字符串连接起来放入新的空间，如此反复，内存操作比较频繁，每次都要计算内存空间，然后开辟内存空间，再释放内存空间，效率非常低，你也许操作比较少的数据的时候看不出来，感觉影响不大，但是你碰到操作数据量比较多的时候，这个方法就要退休了。

2：字符串截取

我们可以通过索引来提取想要获取的字符，可以把python的字符串也做为字符串的列表就更好理解

python的字串列表有2种取值顺序：

1是从左到右索引默认0开始的，最大范围是字符串长度少1

s = 'ilovepython'
s[0]的结果是i

2是从右到左索引默认-1开始的，最大范围是字符串开头

s = 'ilovepython'
s[-1]的结果是n

上面这个是取得一个字符，如果你的实际要取得一段子串的话，可以用到变量[头下标:尾下标]，就可以截取相应的字符串，其中下标是从0开始算起，可以是正数或负数，下标可以为空表示取到头或尾。

比如

s = 'ilovepython'
s[1:5]的结果是love

当使用以冒号分隔的字符串，python返回一个新的对象，结果包含了以这对偏移标识的连续的内容，左边的开始是包含了下边界，比如上面的结果包含了s[1]的值l，而取到的最大范围不包括上边界，就是s[5]的值p

注：s[1:5]形式截头不截尾

3：字符串替换

方法一：使用repalce方法

 a = 'hello world'
 b = a.replace('world','python')
 print(b)

方法二：使用正则表达式

 import re
 a = 'hello world'
 strinfo = re.compile('world')
 b = strinfo.sub('python',a)
 print(b)

4：字符串比较

cmp方法比较两个对象，并根据结果返回一个整数。cmp(x,y)如果X< Y,返回值是负数如果X>Y 返回的值为正数。

 str1 = 'strch'
 str2 = 'strchr'
 print(cmp(str1,str2))
 ## -1

5：字符串相加

我们通过操作符号+来进行字符串的相加，不过建议还是用其他的方式来进行字符串的拼接，这样效率高点。
原因：在循环连接字符串的时候，他每次连接一次，就要重新开辟空间，然后把字符串连接起来，再放入新的空间，再一次循环，又要开辟新的空间，把字符串连接起来放入新的空间，如此反复，内存操作比较频繁，每次都要计算内存空间，然后开辟内存空间，再释放内存空间，效率非常低。

str1 = 'strch'
 str2 = 'strchr'
 print(str1+str2)
 ## strchstrchr

6：字符串查找

python 字符串查找有4个方法，1 find,2 index方法，3 rfind方法,4 rindex方法。

方法一：find方法

info = 'abca'
 print info.find('a')##从下标0开始，查找在字符串里第一个出现的子串，返回结果：0
 
 info = 'abca'
 print info.find('a',1)##从下标1开始，查找在字符串里第一个出现的子串：返回结果3
 
 info = 'abca'
 print info.find('')##返回-1,查找不到返回-1

方法二：index方法

python 的index方法是在字符串里查找子串第一次出现的位置，类似字符串的find方法，不过比find方法更好的是，如果查找不到子串，会抛出异常，而不是返回-1

 info = 'abca'
 print info.index('a')
 print info.index('')

7：字符串分割

字符串分割，可以用split,rsplit方法，通过相应的规则来切割成生成列表对象

info = 'name:haha,age:20$name:python,age:30$name:fef,age:55'
 content = info.split('$')
 print content
 ## ['name:haha,age:20', 'name:python,age:30', 'name:fef,age:55']

8：字符串反转

 a = 'abcd'
 b = a[::-1]##[::-1]通过步进反转
 print b

9：字符串编码

10：字符串追加和拼接

通过字符串的占位符来进行字符串的拼接

#1 元组拼接
m = 'python'
astr = 'i love %s' % m
print astr
 
#2 字符串的format方法
m = 'python'
astr = "i love {python}".format(python=m)
print astr
 
#3 字典格式化字符串
m = 'python'
astr = "i love %(python)s " % {'python':m}
print astr

11：字符串复制

#通过变量来进行赋值
fstr = 'strcpy'
sstr = fstr
fstr = 'strcpy2'
print sstr

12：字符串长度

#通过内置方法len()来计算字符串的长度，注意这个计算的是字符的长度。
aa = 'afebb'
bb = '你'
print len(aa)
print len(bb)

13：字符串大小写

#通过下面的upper(),lower()等方法来转换大小写
S.upper()#S中的字母大写
S.lower() #S中的字母小写
S.capitalize() #首字母大写
S.istitle() #S是否是首字母大写的
S.isupper() #S中的字母是否便是大写
S.islower() #S中的字母是否全是小写

14：字符串去空格

#通过strip(),lstrip(),rstrip()方法去除字符串的空格
S.strip()    #去掉字符串的左右空格
S.lstrip()    #去掉字符串的左边空格
S.rstrip()    #去掉字符串的右边空格
#注意：strip()函数不仅可以去空格还可以去除指定的字符，如
S.strip("\n")

15：字符串其他方法

#字符串相关的其他方法:count(),join()方法等。
S.center(width, [fillchar]) #中间对齐
S.count(substr, [start, [end]]) #计算substr在S中出现的次数
S.expandtabs([tabsize]) #把S中的tab字符替换没空格，每个tab替换为tabsize个空格，默认是8个
S.isalnum() #是否全是字母和数字，并至少有一个字符
S.isalpha() #是否全是字母，并至少有一个字符
S.isspace() #是否全是空白字符，并至少有一个字符
S.join()#S中的join，把列表生成一个字符串对象
S.ljust(width,[fillchar]) #输出width个字符，S左对齐，不足部分用fillchar填充，默认的为空格。
S.rjust(width,[fillchar]) #右对齐
S.splitlines([keepends]) #把S按照行分割符分为一个list，keepends是一个bool值，如果为真每行后而会保留行分割符。
S.swapcase() #大小写互换

三：列表 list

class list(object):
    """
    list() -> new empty list
    list(iterable) -> new list initialized from iterable's items
    """
    def append(self, p_object): # real signature unknown; restored from __doc__
        """ L.append(object) -- append object to end """
        pass
 
    def count(self, value): # real signature unknown; restored from __doc__
        """ L.count(value) -> integer -- return number of occurrences of value """
        return 0
 
    def extend(self, iterable): # real signature unknown; restored from __doc__
        """ L.extend(iterable) -- extend list by appending elements from the iterable """
        pass
 
    def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__
        """
        L.index(value, [start, [stop]]) -> integer -- return first index of value.
        Raises ValueError if the value is not present.
        """
        return 0
 
    def insert(self, index, p_object): # real signature unknown; restored from __doc__
        """ L.insert(index, object) -- insert object before index """
        pass
 
    def pop(self, index=None): # real signature unknown; restored from __doc__
        """
        L.pop([index]) -> item -- remove and return item at index (default last).
        Raises IndexError if list is empty or index is out of range.
        """
        pass
 
    def remove(self, value): # real signature unknown; restored from __doc__
        """
        L.remove(value) -- remove first occurrence of value.
        Raises ValueError if the value is not present.
        """
        pass
 
    def reverse(self): # real signature unknown; restored from __doc__
        """ L.reverse() -- reverse *IN PLACE* """
        pass
 
    def sort(self, cmp=None, key=None, reverse=False): # real signature unknown; restored from __doc__
        """
        L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*;
        cmp(x, y) -> -1, 0, 1
        """
        pass
 
    def __add__(self, y): # real signature unknown; restored from __doc__
        """ x.__add__(y) <==> x+y """
        pass
 
    def __contains__(self, y): # real signature unknown; restored from __doc__
        """ x.__contains__(y) <==> y in x """
        pass
 
    def __delitem__(self, y): # real signature unknown; restored from __doc__
        """ x.__delitem__(y) <==> del x[y] """
        pass
 
    def __delslice__(self, i, j): # real signature unknown; restored from __doc__
        """
        x.__delslice__(i, j) <==> del x[i:j]
 
                   Use of negative indices is not supported.
        """
        pass
 
    def __eq__(self, y): # real signature unknown; restored from __doc__
        """ x.__eq__(y) <==> x==y """
        pass
 
    def __getattribute__(self, name): # real signature unknown; restored from __doc__
        """ x.__getattribute__('name') <==> x.name """
        pass
 
    def __getitem__(self, y): # real signature unknown; restored from __doc__
        """ x.__getitem__(y) <==> x[y] """
        pass
 
    def __getslice__(self, i, j): # real signature unknown; restored from __doc__
        """
        x.__getslice__(i, j) <==> x[i:j]
 
                   Use of negative indices is not supported.
        """
        pass
 
    def __ge__(self, y): # real signature unknown; restored from __doc__
        """ x.__ge__(y) <==> x>=y """
        pass
 
    def __gt__(self, y): # real signature unknown; restored from __doc__
        """ x.__gt__(y) <==> x>y """
        pass
 
    def __iadd__(self, y): # real signature unknown; restored from __doc__
        """ x.__iadd__(y) <==> x+=y """
        pass
 
    def __imul__(self, y): # real signature unknown; restored from __doc__
        """ x.__imul__(y) <==> x*=y """
        pass
 
    def __init__(self, seq=()): # known special case of list.__init__
        """
        list() -> new empty list
        list(iterable) -> new list initialized from iterable's items
        # (copied from class doc)
        """
        pass
 
    def __iter__(self): # real signature unknown; restored from __doc__
        """ x.__iter__() <==> iter(x) """
        pass
 
    def __len__(self): # real signature unknown; restored from __doc__
        """ x.__len__() <==> len(x) """
        pass
 
    def __le__(self, y): # real signature unknown; restored from __doc__
        """ x.__le__(y) <==> x<=y """
        pass
 
    def __lt__(self, y): # real signature unknown; restored from __doc__
        """ x.__lt__(y) <==> x<y """
        pass
 
    def __mul__(self, n): # real signature unknown; restored from __doc__
        """ x.__mul__(n) <==> x*n """
        pass
 
    @staticmethod # known case of __new__
    def __new__(S, *more): # real signature unknown; restored from __doc__
        """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
        pass
 
    def __ne__(self, y): # real signature unknown; restored from __doc__
        """ x.__ne__(y) <==> x!=y """
        pass
 
    def __repr__(self): # real signature unknown; restored from __doc__
        """ x.__repr__() <==> repr(x) """
        pass
 
    def __reversed__(self): # real signature unknown; restored from __doc__
        """ L.__reversed__() -- return a reverse iterator over the list """
        pass
 
    def __rmul__(self, n): # real signature unknown; restored from __doc__
        """ x.__rmul__(n) <==> n*x """
        pass
 
    def __setitem__(self, i, y): # real signature unknown; restored from __doc__
        """ x.__setitem__(i, y) <==> x[i]=y """
        pass
 
    def __setslice__(self, i, j, y): # real signature unknown; restored from __doc__
        """
        x.__setslice__(i, j, y) <==> x[i:j]=y
 
                   Use  of negative indices is not supported.
        """
        pass
 
    def __sizeof__(self): # real signature unknown; restored from __doc__
        """ L.__sizeof__() -- size of L in memory, in bytes """
        pass
 
    __hash__ = None
 
list

list

1：创建列表

list1 = ['physics', 'chemistry', 1997, 2000];
list2 = [1, 2, 3, 4, 5 ];
list3 = ["a", "b", "c", "d"];

与字符串的索引一样，列表索引从0开始。列表可以进行截取、组合等

2：访问列表

list1 = ['physics', 'chemistry', 1997, 2000];
list2 = [1, 2, 3, 4, 5, 6, 7 ];
print(list1[0])
print(list2[2:5])#截头不截尾
## physics
## [3, 4, 5]

3：append方法：在列表末尾添加新的对象

aList = [123, 'xyz', 'zara', 'abc'];
aList.append( 2009 );
print "Updated List : ", aList;
## Updated List :  [123, 'xyz', 'zara', 'abc', 2009]

4：count方法：统计某个元素在列表中出现的次数

aList = [123, 'xyz', 'zara', 123];
print(aList.count(123))
## 2

5：extend() 函数用于在列表末尾一次性追加另一个序列中的多个值（用新列表扩展原来的列表）

aList = [123, 'xyz', 'zara', 'abc', 123];
bList = [2009, 'manni'];
aList.extend(bList)
 
print "Extended List : ", aList ;
## Extended List :  [123, 'xyz', 'zara', 'abc', 123, 2009, 'manni']

6：index() 函数用于从列表中找出某个值第一个匹配项的索引位置

aList = [123, 'xyz', 'zara', 'abc'];
 
print "Index for xyz : ", aList.index( 'xyz' ) ;
print "Index for zara : ", aList.index( 'zara' ) ;
 
##Index for xyz :  1
## Index for zara :  2

7：insert() 函数用于将指定对象插入列表的指定位置

aList = [123, 'xyz', 'zara', 'abc']
 
aList.insert( 3, 2009)
 
print "Final List : ", aList
 
## Final List : [123, 'xyz', 'zara', 2009, 'abc']

insert()接收两个参数，list.insert(index, obj)，第一个参数index为要插入的索引位置，第二个参数要插入的元素

8：pop() 函数用于移除列表中的一个元素（默认最后一个元素），并且返回该元素的值

aList = [123, 'xyz', 'zara', 'abc'];
print "A List : ", aList.pop();
print "B List : ", aList.pop();
## A List : abc
## B List : zara

9：remove() 函数用于移除列表中某个值的第一个匹配项

aList = [123, 'xyz', 'zara', 'abc', 'xyz'];
aList.remove('xyz');
print "List : ", aList;
aList.remove('abc');
print "List : ", aList;
## List : [123, 'zara', 'abc', 'xyz']
## List : [123, 'zara', 'xyz']

10：列表的四种遍历方法

aList = [123, 'xyz', 'zara', 123];

方法一：只遍历列表中的值

for value in aList :
print(value)
####################
123
xyz
zara
123

方法二：如果需要遍历列表中的索引与值，就需要用到enumerate

for key,value in enumerate(aList) :
print(key,value)
######################
(0, 123)
(1, 'xyz')
(2, 'zara')
(3, 123)

enumrate：为可迭代的对象添加序号，默认从0开始！因为列表的索引也是从0开始，所以我们在enumerate中不指定第二个参数，如有需要，可以指定从几开始，如下：

for key,value in enumerate(aList,1) :
print(key,value)
######################################
(1, 123)
(2, 'xyz')
(3, 'zara')
(4, 123)

方法三：

for i in range(len(aList)) :
print(i,aList[i])
##############################
(0, 123)
(1, 'xyz')
(2, 'zara')
(3, 123)

range和xrange：指定范围，生成指定的数字

方法四：使用iter()

for i in iter(aList) :
print(i)
##########################################
123
xyz
zara
123

四：元组 tuple

lass tuple(object):
"""
tuple() -> empty tuple
tuple(iterable) -> tuple initialized from iterable's items
If the argument is a tuple, the return value is the same object.
"""
def count(self, value): # real signature unknown; restored from __doc__
""" T.count(value) -> integer -- return number of occurrences of value """
return 0
def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__
"""
T.index(value, [start, [stop]]) -> integer -- return first index of value.
Raises ValueError if the value is not present.
"""
return 0
def __add__(self, y): # real signature unknown; restored from __doc__
""" x.__add__(y) <==> x+y """
pass
def __contains__(self, y): # real signature unknown; restored from __doc__
""" x.__contains__(y) <==> y in x """
pass
def __eq__(self, y): # real signature unknown; restored from __doc__
""" x.__eq__(y) <==> x==y """
pass
def __getattribute__(self, name): # real signature unknown; restored from __doc__
""" x.__getattribute__('name') <==> x.name """
pass
def __getitem__(self, y): # real signature unknown; restored from __doc__
""" x.__getitem__(y) <==> x[y] """
pass
def __getnewargs__(self, *args, **kwargs): # real signature unknown
pass
def __getslice__(self, i, j): # real signature unknown; restored from __doc__
"""
x.__getslice__(i, j) <==> x[i:j]
Use of negative indices is not supported.
"""
pass
def __ge__(self, y): # real signature unknown; restored from __doc__
""" x.__ge__(y) <==> x>=y """
pass
def __gt__(self, y): # real signature unknown; restored from __doc__
""" x.__gt__(y) <==> x>y """
pass
def __hash__(self): # real signature unknown; restored from __doc__
""" x.__hash__() <==> hash(x) """
pass
def __init__(self, seq=()): # known special case of tuple.__init__
"""
tuple() -> empty tuple
tuple(iterable) -> tuple initialized from iterable's items
If the argument is a tuple, the return value is the same object.
# (copied from class doc)
"""
pass
def __iter__(self): # real signature unknown; restored from __doc__
""" x.__iter__() <==> iter(x) """
pass
def __len__(self): # real signature unknown; restored from __doc__
""" x.__len__() <==> len(x) """
pass
def __le__(self, y): # real signature unknown; restored from __doc__
""" x.__le__(y) <==> x<=y """
pass
def __lt__(self, y): # real signature unknown; restored from __doc__
""" x.__lt__(y) <==> x<y """
pass
def __mul__(self, n): # real signature unknown; restored from __doc__
""" x.__mul__(n) <==> x*n """
pass
@staticmethod # known case of __new__
def __new__(S, *more): # real signature unknown; restored from __doc__
""" T.__new__(S, ...) -> a new object with type S, a subtype of T """
pass
def __ne__(self, y): # real signature unknown; restored from __doc__
""" x.__ne__(y) <==> x!=y """
pass
def __repr__(self): # real signature unknown; restored from __doc__
""" x.__repr__() <==> repr(x) """
pass
def __rmul__(self, n): # real signature unknown; restored from __doc__
""" x.__rmul__(n) <==> n*x """
pass
def __sizeof__(self): # real signature unknown; restored from __doc__
""" T.__sizeof__() -- size of T in memory, in bytes """
pass
tuple

tuple

Python的元组与列表类似，不同之处在于元组的元素不能修改。元组使用小括号，列表使用方括号。元组创建很简单，只需要在括号中添加元素，并使用逗号隔开即可

tuple只有两个可使用的功能：count , index

1：创建元组

tup1 = ();#创建空元组
tup1 = (50,);#元组中只包含一个元素时，需要在元素后面添加逗号

元组与字符串类似，下标索引从0开始，可以进行截取，组合等。元组的访问与列表一样！

2：元组的连接组合

tup1 = (12, 34.56);
tup2 = ('abc', 'xyz');
# 以下修改元组元素操作是非法的。
# tup1[0] = 100;
# 创建一个新的元组
tup3 = tup1 + tup2;
print tup3;
##########################################
(12, 34.56, 'abc', 'xyz')

3：删除元组

元组中的元素值是不允许删除的，但我们可以使用del语句来删除整个元组，如下实例:

tup = ('physics', 'chemistry', 1997, 2000);
print tup;
del tup;
print "After deleting tup : "
print tup;
##########################################
以上实例元组被删除后，输出变量会有异常信息，输出如下所示：
('physics', 'chemistry', 1997, 2000)
After deleting tup :
Traceback (most recent call last):
File "test.py", line 9, in <module>
print tup;
NameError: name 'tup' is not defined

五：字典 dict

class dict(object):
"""
dict() -> new empty dictionary
dict(mapping) -> new dictionary initialized from a mapping object's
(key, value) pairs
dict(iterable) -> new dictionary initialized as if via:
d = {}
for k, v in iterable:
d[k] = v
dict(**kwargs) -> new dictionary initialized with the name=value pairs
in the keyword argument list. For example: dict(one=1, two=2)
"""
def clear(self): # real signature unknown; restored from __doc__
""" 清除内容 """
""" D.clear() -> None. Remove all items from D. """
pass
def copy(self): # real signature unknown; restored from __doc__
""" 浅拷贝 """
""" D.copy() -> a shallow copy of D """
pass
@staticmethod # known case
def fromkeys(S, v=None): # real signature unknown; restored from __doc__
"""
dict.fromkeys(S[,v]) -> New dict with keys from S and values equal to v.
v defaults to None.
"""
pass
def get(self, k, d=None): # real signature unknown; restored from __doc__
""" 根据key获取值，d是默认值 """
""" D.get(k[,d]) -> D[k] if k in D, else d. d defaults to None. """
pass
def has_key(self, k): # real signature unknown; restored from __doc__
""" 是否有key """
""" D.has_key(k) -> True if D has a key k, else False """
return False
def items(self): # real signature unknown; restored from __doc__
""" 所有项的列表形式 """
""" D.items() -> list of D's (key, value) pairs, as 2-tuples """
return []
def iteritems(self): # real signature unknown; restored from __doc__
""" 项可迭代 """
""" D.iteritems() -> an iterator over the (key, value) items of D """
pass
def iterkeys(self): # real signature unknown; restored from __doc__
""" key可迭代 """
""" D.iterkeys() -> an iterator over the keys of D """
pass
def itervalues(self): # real signature unknown; restored from __doc__
""" value可迭代 """
""" D.itervalues() -> an iterator over the values of D """
pass
def keys(self): # real signature unknown; restored from __doc__
""" 所有的key列表 """
""" D.keys() -> list of D's keys """
return []
def pop(self, k, d=None): # real signature unknown; restored from __doc__
""" 获取并在字典中移除 """
"""
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
"""
pass
def popitem(self): # real signature unknown; restored from __doc__
""" 获取并在字典中移除 """
"""
D.popitem() -> (k, v), remove and return some (key, value) pair as a
2-tuple; but raise KeyError if D is empty.
"""
pass
def setdefault(self, k, d=None): # real signature unknown; restored from __doc__
""" 如果key不存在，则创建，如果存在，则返回已存在的值且不修改 """
""" D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D """
pass
def update(self, E=None, **F): # known special case of dict.update
""" 更新
{'name':'alex', 'age': 18000}
[('name','sbsbsb'),]
"""
"""
D.update([E, ]**F) -> None. Update D from dict/iterable E and F.
If E present and has a .keys() method, does: for k in E: D[k] = E[k]
If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v
In either case, this is followed by: for k in F: D[k] = F[k]
"""
pass
def values(self): # real signature unknown; restored from __doc__
""" 所有的值 """
""" D.values() -> list of D's values """
return []
def viewitems(self): # real signature unknown; restored from __doc__
""" 所有项，只是将内容保存至view对象中 """
""" D.viewitems() -> a set-like object providing a view on D's items """
pass
def viewkeys(self): # real signature unknown; restored from __doc__
""" D.viewkeys() -> a set-like object providing a view on D's keys """
pass
def viewvalues(self): # real signature unknown; restored from __doc__
""" D.viewvalues() -> an object providing a view on D's values """
pass
def __cmp__(self, y): # real signature unknown; restored from __doc__
""" x.__cmp__(y) <==> cmp(x,y) """
pass
def __contains__(self, k): # real signature unknown; restored from __doc__
""" D.__contains__(k) -> True if D has a key k, else False """
return False
def __delitem__(self, y): # real signature unknown; restored from __doc__
""" x.__delitem__(y) <==> del x[y] """
pass
def __eq__(self, y): # real signature unknown; restored from __doc__
""" x.__eq__(y) <==> x==y """
pass
def __getattribute__(self, name): # real signature unknown; restored from __doc__
""" x.__getattribute__('name') <==> x.name """
pass
def __getitem__(self, y): # real signature unknown; restored from __doc__
""" x.__getitem__(y) <==> x[y] """
pass
def __ge__(self, y): # real signature unknown; restored from __doc__
""" x.__ge__(y) <==> x>=y """
pass
def __gt__(self, y): # real signature unknown; restored from __doc__
""" x.__gt__(y) <==> x>y """
pass
def __init__(self, seq=None, **kwargs): # known special case of dict.__init__
"""
dict() -> new empty dictionary
dict(mapping) -> new dictionary initialized from a mapping object's
(key, value) pairs
dict(iterable) -> new dictionary initialized as if via:
d = {}
for k, v in iterable:
d[k] = v
dict(**kwargs) -> new dictionary initialized with the name=value pairs
in the keyword argument list. For example: dict(one=1, two=2)
# (copied from class doc)
"""
pass
def __iter__(self): # real signature unknown; restored from __doc__
""" x.__iter__() <==> iter(x) """
pass
def __len__(self): # real signature unknown; restored from __doc__
""" x.__len__() <==> len(x) """
pass
def __le__(self, y): # real signature unknown; restored from __doc__
""" x.__le__(y) <==> x<=y """
pass
def __lt__(self, y): # real signature unknown; restored from __doc__
""" x.__lt__(y) <==> x<y """
pass
@staticmethod # known case of __new__
def __new__(S, *more): # real signature unknown; restored from __doc__
""" T.__new__(S, ...) -> a new object with type S, a subtype of T """
pass
def __ne__(self, y): # real signature unknown; restored from __doc__
""" x.__ne__(y) <==> x!=y """
pass
def __repr__(self): # real signature unknown; restored from __doc__
""" x.__repr__() <==> repr(x) """
pass
def __setitem__(self, i, y): # real signature unknown; restored from __doc__
""" x.__setitem__(i, y) <==> x[i]=y """
pass
def __sizeof__(self): # real signature unknown; restored from __doc__
""" D.__sizeof__() -> size of D in memory, in bytes """
pass
__hash__ = None
dict