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any operand is a complex number, the objects are of different types that cannot
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be compared, or other cases where there is no defined ordering.
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single: __eq__() (instance method)
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single: __ne__() (instance method)
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single: __lt__() (instance method)
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for well-defined conversions.
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float also accepts the strings "nan" and "inf" with an optional prefix "+"
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float also accepts the strings "nan" and "inf" with an optional prefix "+"
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or "-" for Not a Number (NaN) and positive or negative infinity.
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Python defines ``pow(0, 0)`` and ``0 ** 0`` to be ``1``, as is common for
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programming languages.
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All :class:`numbers.Real` types (:class:`int` and
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:class:`float`) also include the following operations:
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+--------------------+--------------------------------+--------+
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| Operation | Result | Notes |
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+====================+================================+========+
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| ``trunc(x)`` | *x* truncated to Integral | |
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+--------------------+--------------------------------+--------+
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| ``round(x[, n])`` | *x* rounded to n digits, | |
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| | rounding half to even. If n is | |
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| | omitted, it defaults to 0. | |
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+--------------------+--------------------------------+--------+
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| ``math.floor(x)`` | the greatest Integral <= *x* | |
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+--------------------+--------------------------------+--------+
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| ``math.ceil(x)`` | the least Integral >= *x* | |
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+--------------------+--------------------------------+--------+
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+--------------------+------------------------------------+--------+
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| Operation | Result | Notes |
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+====================+====================================+========+
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| ``math.trunc(x)`` | *x* truncated to Integral | |
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+--------------------+------------------------------------+--------+
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| ``round(x[, n])`` | *x* rounded to n digits, | |
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| | rounding half to even. If n is | |
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| | omitted, it defaults to 0. | |
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+--------------------+------------------------------------+--------+
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| ``math.floor(x)`` | the greatest integral float <= *x* | |
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+--------------------+------------------------------------+--------+
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| ``math.ceil(x)`` | the least integral float >= *x* | |
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+--------------------+------------------------------------+--------+
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For additional numeric operations see the :mod:`math` and :mod:`cmath`
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Additional Methods on Integer Types
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-----------------------------------
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.. method:: int.bit_length()
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Return the number of bits necessary to represent an integer in binary,
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excluding the sign and leading zeros::
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More precisely, if ``x`` is nonzero, then ``x.bit_length()`` is the
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unique positive integer ``k`` such that ``2**(k-1) <= abs(x) < 2**k``.
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Equivalently, when ``abs(x)`` is small enough to have a correctly
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rounded logarithm, then ``k = 1 + int(log(abs(x), 2))``.
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If ``x`` is zero, then ``x.bit_length()`` returns ``0``.
445
def bit_length(self):
446
s = bin(x) # binary representation: bin(-37) --> '-0b100101'
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s = s.lstrip('-0b') # remove leading zeros and minus sign
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return len(s) # len('100101') --> 6
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.. versionadded:: 3.1
422
453
Additional Methods on Float
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454
---------------------------
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Sequence Types --- :class:`str`, :class:`bytes`, :class:`bytearray`, :class:`list`, :class:`tuple`, :class:`range`
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==================================================================================================================
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There are five sequence types: strings, byte sequences, byte arrays, lists,
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tuples, and range objects. (For other containers see the built-in
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:class:`dict`, :class:`list`, :class:`set`, and :class:`tuple` classes, and the
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:mod:`collections` module.)
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There are six sequence types: strings, byte sequences (:class:`bytes` objects),
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byte arrays (:class:`bytearray` objects), lists, tuples, and range objects. For
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other containers see the built in :class:`dict` and :class:`set` classes, and
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the :mod:`collections` module.
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that have the Unicode numeric value property, e.g. U+2155,
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904
VULGAR FRACTION ONE FIFTH.
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.. method:: str.isprintable()
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Return true if all characters in the string are printable or the string is
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1116
.. method:: str.translate(map)
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Return a copy of the *s* where all characters have been mapped through the
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*map* which must be a dictionary of Unicode ordinals(integers) to Unicode
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*map* which must be a dictionary of Unicode ordinals (integers) to Unicode
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ordinals, strings or ``None``. Unmapped characters are left untouched.
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Characters mapped to ``None`` are deleted.
1093
A *map* for :meth:`translate` is usually best created by
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:meth:`str.maketrans`.
1096
You can use the :func:`maketrans` helper function in the :mod:`string` module to
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create a translation table. For string objects, set the *table* argument to
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``None`` for translations that only delete characters:
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You can use :meth:`str.maketrans` to create a translation map from
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character-to-character mappings in different formats.
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example, sort by department, then by salary grade).
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While a list is being sorted, the effect of attempting to mutate, or even
1451
inspect, the list is undefined. The C implementation
1477
inspect, the list is undefined. The C implementation
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makes the list appear empty for the duration, and raises :exc:`ValueError` if it
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can detect that the list has been mutated during a sort.
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1524
>>> bytes.fromhex('f0 f1f2 ')
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b'\xf0\xf1\xf2'
1501
.. XXX verify/document translate() semantics!
1503
.. method:: bytes.translate(table[, delete])
1505
Return a copy of the bytes object where all bytes occurring in the optional
1506
argument *delete* are removed, and the remaining bytes have been mapped
1507
through the given translation table, which must be a bytes object of length
1510
You can use the :func:`maketrans` helper function in the :mod:`string` module to
1511
create a translation table.
1513
.. XXX a None table doesn't seem to be supported
1514
Set the *table* argument to ``None`` for translations that only delete characters::
1516
>>> 'read this short text'.translate(None, 'aeiou')
1527
The translate method differs in semantics from the version available on strings:
1529
.. method:: bytes.translate(table[, delete])
1531
Return a copy of the bytes or bytearray object where all bytes occurring in
1532
the optional argument *delete* are removed, and the remaining bytes have been
1533
mapped through the given translation table, which must be a bytes object of
1536
You can use the :func:`string.maketrans` helper function to create a
1539
Set the *table* argument to ``None`` for translations that only delete
1542
>>> b'read this short text'.translate(None, b'aeiou')
1597
1623
.. method:: union(other, ...)
1598
1624
set | other | ...
1600
Return a new set with elements from both sets.
1626
Return a new set with elements from the set and all others.
1602
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.. method:: intersection(other, ...)
1603
1629
set & other & ...
1605
Return a new set with elements common to both sets.
1631
Return a new set with elements common to the set and all others.
1607
1633
.. method:: difference(other, ...)
1608
1634
set - other - ...
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Return the item of *d* with key *key*. Raises a :exc:`KeyError` if *key* is
1783
1809
not in the map.
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If a subclass of dict defines a method :meth:`__missing__`, if the key *key*
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is not present, the ``d[key]`` operation calls that method with the key *key*
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as argument. The ``d[key]`` operation then returns or raises whatever is
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positioning); other values are ``os.SEEK_CUR`` or ``1`` (seek relative to the
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current position) and ``os.SEEK_END`` or ``2`` (seek relative to the file's
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end). There is no return value.
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For example, ``f.seek(2, os.SEEK_CUR)`` advances the position by two and
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``f.seek(-3, os.SEEK_END)`` sets the position to the third to last.
added
removed
Doc/library/stdtypes.rst
