Help on class float in module __builtin__:
class float(object)
| float(x) -> floating point number
|
| Convert a string or number to a floating point number, if possible.
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| Methods defined here:
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| __abs__(...)
| x.__abs__() <==> abs(x)
|
| __add__(...)
| x.__add__(y) <==> x+y
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| __coerce__(...)
| x.__coerce__(y) <==> coerce(x, y)
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| __div__(...)
| x.__div__(y) <==> x/y
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| __divmod__(...)
| x.__divmod__(y) <==> divmod(x, y)
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| __eq__(...)
| x.__eq__(y) <==> x==y
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| __float__(...)
| x.__float__() <==> float(x)
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| __floordiv__(...)
| x.__floordiv__(y) <==> x//y
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| __format__(...)
| float.__format__(format_spec) -> string
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| Formats the float according to format_spec.
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| __ge__(...)
| x.__ge__(y) <==> x>=y
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| __getattribute__(...)
| x.__getattribute__('name') <==> x.name
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| __getformat__(...)
| float.__getformat__(typestr) -> string
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| You probably don't want to use this function. It exists mainly to be
| used in Python's test suite.
|
| typestr must be 'double' or 'float'. This function returns whichever of
| 'unknown', 'IEEE, big-endian' or 'IEEE, little-endian' best describes the
| format of floating point numbers used by the C type named by typestr.
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| __getnewargs__(...)
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| __gt__(...)
| x.__gt__(y) <==> x>y
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| __hash__(...)
| x.__hash__() <==> hash(x)
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| __int__(...)
| x.__int__() <==> int(x)
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| __le__(...)
| x.__le__(y) <==> x<=y
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| __long__(...)
| x.__long__() <==> long(x)
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| __lt__(...)
| x.__lt__(y) <==> x | | __mod__(...) | x.__mod__(y) <==> x%y | | __mul__(...) | x.__mul__(y) <==> x*y | | __ne__(...) | x.__ne__(y) <==> x!=y | | __neg__(...) | x.__neg__() <==> -x | | __nonzero__(...) | x.__nonzero__() <==> x != 0 | | __pos__(...) | x.__pos__() <==> +x | | __pow__(...) | x.__pow__(y[, z]) <==> pow(x, y[, z]) | | __radd__(...) | x.__radd__(y) <==> y+x | | __rdiv__(...) | x.__rdiv__(y) <==> y/x | | __rdivmod__(...) | x.__rdivmod__(y) <==> divmod(y, x) | | __repr__(...) | x.__repr__() <==> repr(x) | | __rfloordiv__(...) | x.__rfloordiv__(y) <==> y//x | | __rmod__(...) | x.__rmod__(y) <==> y%x | | __rmul__(...) | x.__rmul__(y) <==> y*x | | __rpow__(...) | y.__rpow__(x[, z]) <==> pow(x, y[, z]) | | __rsub__(...) | x.__rsub__(y) <==> y-x | | __rtruediv__(...) | x.__rtruediv__(y) <==> y/x | | __setformat__(...) | float.__setformat__(typestr, fmt) -> None | | You probably don't want to use this function. It exists mainly to be | used in Python's test suite. | | typestr must be 'double' or 'float'. fmt must be one of 'unknown', | 'IEEE, big-endian' or 'IEEE, little-endian', and in addition can only be | one of the latter two if it appears to match the underlying C reality. | | Overrides the automatic determination of C-level floating point type. | This affects how floats are converted to and from binary strings. | | __str__(...) | x.__str__() <==> str(x) | | __sub__(...) | x.__sub__(y) <==> x-y | | __truediv__(...) | x.__truediv__(y) <==> x/y | | __trunc__(...) | Returns the Integral closest to x between 0 and x. | | as_integer_ratio(...) | float.as_integer_ratio() -> (int, int) | | Returns a pair of integers, whose ratio is exactly equal to the original | float and with a positive denominator. | Raises OverflowError on infinities and a ValueError on NaNs. | | >>> (10.0).as_integer_ratio() | (10, 1) | >>> (0.0).as_integer_ratio() | (0, 1) | >>> (-.25).as_integer_ratio() | (-1, 4) | | conjugate(...) | Returns self, the complex conjugate of any float. | | fromhex(...) | float.fromhex(string) -> float | | Create a floating-point number from a hexadecimal string. | >>> float.fromhex('0x1.ffffp10') | 2047.984375 | >>> float.fromhex('-0x1p-1074') | -4.9406564584124654e-324 | | hex(...) | float.hex() -> string | | Return a hexadecimal representation of a floating-point number. | >>> (-0.1).hex() | '-0x1.999999999999ap-4' | >>> 3.14159.hex() | '0x1.921f9f01b866ep+1' | | is_integer(...) | Returns True if the float is an integer. | | ---------------------------------------------------------------------- | Data descriptors defined here: | | imag | the imaginary part of a complex number | | real | the real part of a complex number | | ---------------------------------------------------------------------- | Data and other attributes defined here: | | __new__ = | T.__new__(S, ...) -> a new object with type S, a subtype of T filter(function, iterable) Construct a list from those elements of iterable for which function returns true. iterable may be either a sequence, a container which supports iteration, or an iterator. If iterable is a string or a tuple, the result also has that type; otherwise it is always a list. If function is None, the identity function is assumed, that is, all elements of iterable that are false are removed. Note that filter(function, iterable) is equivalent to [item for item in iterable if function(item)] if function is not None and [item for item in iterable if item] if function is None. See itertools.ifilter() and itertools.ifilterfalse() for iterator versions of this function, including a variation that filters for elements where the function returns false. 中文说明： 本函数是转换一个字符串或一个整数为浮点数。如果参数x是一个字符串，那么只使用十进制表示的数字串，数字前面可以添加符号来表示正数，或负数。如果参数x是整数，可以转换为浮点数表示。不过，这个函数有一个特别的地方，就是使用infinity或inf来表示无穷大的数。比如+inf是正无穷大，-inf是负无穷大。 >>> float(6) 6.0 >>> float('6') 6.0 >>> float() 0.0 >>> float('+5.778') 5.778 >>> float('-5.778') -5.778 >>> float('+inf') inf >>> float('-inf') -inf >>> float('nan') nan >>> class T: ... def __init__(self,score): ... self.score = score ... def __float__(self): ... return self.score ... >>> x=T(10.68) >>> float(x) 10.68