operator — Standard operators as functions
The operator module exports a set of functions implemented in C
corresponding to the intrinsic operators of Python. For example,
operator.add(x, y) is equivalent to the expression x+y. The function
names are those used for special class methods; variants without leading and
trailing __ are also provided for convenience.
The functions fall into categories that perform object comparisons, logical
operations, mathematical operations, sequence operations, and abstract type
tests.
The object comparison functions are useful for all objects, and are named after
the rich comparison operators they support:

operator.lt(a, b)

operator.le(a, b)

operator.eq(a, b)

operator.ne(a, b)

operator.ge(a, b)

operator.gt(a, b)

operator.__lt__(a, b)

operator.__le__(a, b)

operator.__eq__(a, b)

operator.__ne__(a, b)

operator.__ge__(a, b)

operator.__gt__(a, b)
Perform “rich comparisons” between a and b. Specifically, lt(a, b) is
equivalent to a < b, le(a, b) is equivalent to a <= b, eq(a,
b) is equivalent to a == b, ne(a, b) is equivalent to a != b,
gt(a, b) is equivalent to a > b and ge(a, b) is equivalent to a
>= b. Note that unlike the builtin cmp(), these functions can
return any value, which may or may not be interpretable as a Boolean value.
See Comparisons for more information about rich comparisons.
New in version 2.2.
The logical operations are also generally applicable to all objects, and support
truth tests, identity tests, and boolean operations:

operator.not_(obj)

operator.__not__(obj)
 Return the outcome of not obj. (Note that there is no
__not__() method for object instances; only the interpreter core defines
this operation. The result is affected by the __nonzero__() and
__len__() methods.)

operator.truth(obj)
 Return True if obj is true, and False otherwise. This is
equivalent to using the bool constructor.

operator.is_(a, b)
Return a is b. Tests object identity.
New in version 2.3.

operator.is_not(a, b)
Return a is not b. Tests object identity.
New in version 2.3.
The mathematical and bitwise operations are the most numerous:

operator.abs(obj)

operator.__abs__(obj)
 Return the absolute value of obj.

operator.add(a, b)

operator.__add__(a, b)
 Return a + b, for a and b numbers.

operator.and_(a, b)

operator.__and__(a, b)
 Return the bitwise and of a and b.

operator.div(a, b)

operator.__div__(a, b)
 Return a / b when __future__.division is not in effect. This is
also known as “classic” division.

operator.floordiv(a, b)

operator.__floordiv__(a, b)
Return a // b.
New in version 2.2.

operator.inv(obj)

operator.invert(obj)

operator.__inv__(obj)

operator.__invert__(obj)
Return the bitwise inverse of the number obj. This is equivalent to ~obj.
New in version 2.0: The names invert() and __invert__().

operator.lshift(a, b)

operator.__lshift__(a, b)
 Return a shifted left by b.

operator.mod(a, b)

operator.__mod__(a, b)
 Return a % b.

operator.mul(a, b)

operator.__mul__(a, b)
 Return a * b, for a and b numbers.

operator.neg(obj)

operator.__neg__(obj)
 Return obj negated.

operator.or_(a, b)

operator.__or__(a, b)
 Return the bitwise or of a and b.

operator.pos(obj)

operator.__pos__(obj)
 Return obj positive.

operator.pow(a, b)

operator.__pow__(a, b)
Return a ** b, for a and b numbers.
New in version 2.3.

operator.rshift(a, b)

operator.__rshift__(a, b)
 Return a shifted right by b.

operator.sub(a, b)

operator.__sub__(a, b)
 Return a  b.

operator.truediv(a, b)

operator.__truediv__(a, b)
Return a / b when __future__.division is in effect. This is also
known as “true” division.
New in version 2.2.

operator.xor(a, b)

operator.__xor__(a, b)
 Return the bitwise exclusive or of a and b.

operator.index(a)

operator.__index__(a)
Return a converted to an integer. Equivalent to a.__index__().
New in version 2.5.
Operations which work with sequences include:

operator.concat(a, b)

operator.__concat__(a, b)
 Return a + b for a and b sequences.

operator.contains(a, b)

operator.__contains__(a, b)
Return the outcome of the test b in a. Note the reversed operands.
New in version 2.0: The name __contains__().

operator.countOf(a, b)
 Return the number of occurrences of b in a.

operator.delitem(a, b)

operator.__delitem__(a, b)
 Remove the value of a at index b.

operator.delslice(a, b, c)

operator.__delslice__(a, b, c)
 Delete the slice of a from index b to index c1.

operator.getitem(a, b)

operator.__getitem__(a, b)
 Return the value of a at index b.

operator.getslice(a, b, c)

operator.__getslice__(a, b, c)
 Return the slice of a from index b to index c1.

operator.indexOf(a, b)
 Return the index of the first of occurrence of b in a.

operator.repeat(a, b)

operator.__repeat__(a, b)
 Return a * b where a is a sequence and b is an integer.

operator.sequenceIncludes(...)
Deprecated since version 2.0: Use contains() instead.
Alias for contains().

operator.setitem(a, b, c)

operator.__setitem__(a, b, c)
 Set the value of a at index b to c.

operator.setslice(a, b, c, v)

operator.__setslice__(a, b, c, v)
 Set the slice of a from index b to index c1 to the sequence v.
Many operations have an “inplace” version. The following functions provide a
more primitive access to inplace operators than the usual syntax does; for
example, the statement x += y is equivalent to
x = operator.iadd(x, y). Another way to put it is to say that
z = operator.iadd(x, y) is equivalent to the compound statement
z = x; z += y.

operator.iadd(a, b)

operator.__iadd__(a, b)
a = iadd(a, b) is equivalent to a += b.
New in version 2.5.

operator.iand(a, b)

operator.__iand__(a, b)
a = iand(a, b) is equivalent to a &= b.
New in version 2.5.

operator.iconcat(a, b)

operator.__iconcat__(a, b)
a = iconcat(a, b) is equivalent to a += b for a and b sequences.
New in version 2.5.

operator.idiv(a, b)

operator.__idiv__(a, b)
a = idiv(a, b) is equivalent to a /= b when __future__.division is
not in effect.
New in version 2.5.

operator.ifloordiv(a, b)

operator.__ifloordiv__(a, b)
a = ifloordiv(a, b) is equivalent to a //= b.
New in version 2.5.

operator.ilshift(a, b)

operator.__ilshift__(a, b)
a = ilshift(a, b) is equivalent to a <<= b.
New in version 2.5.

operator.imod(a, b)

operator.__imod__(a, b)
a = imod(a, b) is equivalent to a %= b.
New in version 2.5.

operator.imul(a, b)

operator.__imul__(a, b)
a = imul(a, b) is equivalent to a *= b.
New in version 2.5.

operator.ior(a, b)

operator.__ior__(a, b)
a = ior(a, b) is equivalent to a = b.
New in version 2.5.

operator.ipow(a, b)

operator.__ipow__(a, b)
a = ipow(a, b) is equivalent to a **= b.
New in version 2.5.

operator.irepeat(a, b)

operator.__irepeat__(a, b)
a = irepeat(a, b) is equivalent to a *= b where a is a sequence and
b is an integer.
New in version 2.5.

operator.irshift(a, b)

operator.__irshift__(a, b)
a = irshift(a, b) is equivalent to a >>= b.
New in version 2.5.

operator.isub(a, b)

operator.__isub__(a, b)
a = isub(a, b) is equivalent to a = b.
New in version 2.5.

operator.itruediv(a, b)

operator.__itruediv__(a, b)
a = itruediv(a, b) is equivalent to a /= b when __future__.division
is in effect.
New in version 2.5.

operator.ixor(a, b)

operator.__ixor__(a, b)
a = ixor(a, b) is equivalent to a ^= b.
New in version 2.5.
The operator module also defines a few predicates to test the type of
objects.
Note
Be careful not to misinterpret the results of these functions; only
isCallable() has any measure of reliability with instance objects.
For example:
>>> class C:
... pass
...
>>> import operator
>>> obj = C()
>>> operator.isMappingType(obj)
True
Note
Python 3 is expected to introduce abstract base classes for
collection types, so it should be possible to write, for example,
isinstance(obj, collections.Mapping) and isinstance(obj,
collections.Sequence).

operator.isCallable(obj)
Deprecated since version 2.0: Use the callable() builtin function instead.
Returns true if the object obj can be called like a function, otherwise it
returns false. True is returned for functions, bound and unbound methods, class
objects, and instance objects which support the __call__() method.

operator.isMappingType(obj)
Returns true if the object obj supports the mapping interface. This is true for
dictionaries and all instance objects defining __getitem__().
Warning
There is no reliable way to test if an instance supports the complete mapping
protocol since the interface itself is illdefined. This makes this test less
useful than it otherwise might be.

operator.isNumberType(obj)
Returns true if the object obj represents a number. This is true for all
numeric types implemented in C.
Warning
There is no reliable way to test if an instance supports the complete numeric
interface since the interface itself is illdefined. This makes this test less
useful than it otherwise might be.

operator.isSequenceType(obj)
Returns true if the object obj supports the sequence protocol. This returns true
for all objects which define sequence methods in C, and for all instance objects
defining __getitem__().
Warning
There is no reliable way to test if an instance supports the complete sequence
interface since the interface itself is illdefined. This makes this test less
useful than it otherwise might be.
Example: Build a dictionary that maps the ordinals from 0 to 255 to
their character equivalents.
>>> d = {}
>>> keys = range(256)
>>> vals = map(chr, keys)
>>> map(operator.setitem, [d]*len(keys), keys, vals) # doctest: +SKIP
The operator module also defines tools for generalized attribute and item
lookups. These are useful for making fast field extractors as arguments for
map(), sorted(), itertools.groupby(), or other functions that
expect a function argument.

operator.attrgetter(attr[, args...])
Return a callable object that fetches attr from its operand. If more than one
attribute is requested, returns a tuple of attributes. After,
f = attrgetter('name'), the call f(b) returns b.name. After,
f = attrgetter('name', 'date'), the call f(b) returns (b.name,
b.date).
The attribute names can also contain dots; after f = attrgetter('date.month'),
the call f(b) returns b.date.month.
New in version 2.4.
Changed in version 2.5: Added support for multiple attributes.
Changed in version 2.6: Added support for dotted attributes.

operator.itemgetter(item[, args...])
Return a callable object that fetches item from its operand using the
operand’s __getitem__() method. If multiple items are specified,
returns a tuple of lookup values. Equivalent to:
def itemgetter(*items):
if len(items) == 1:
item = items[0]
def g(obj):
return obj[item]
else:
def g(obj):
return tuple(obj[item] for item in items)
return g
The items can be any type accepted by the operand’s __getitem__()
method. Dictionaries accept any hashable value. Lists, tuples, and
strings accept an index or a slice:
>>> itemgetter(1)('ABCDEFG')
'B'
>>> itemgetter(1,3,5)('ABCDEFG')
('B', 'D', 'F')
>>> itemgetter(slice(2,None))('ABCDEFG')
'CDEFG'
New in version 2.4.
Changed in version 2.5: Added support for multiple item extraction.
Example of using itemgetter() to retrieve specific fields from a
tuple record:
>>> inventory = [('apple', 3), ('banana', 2), ('pear', 5), ('orange', 1)]
>>> getcount = itemgetter(1)
>>> map(getcount, inventory)
[3, 2, 5, 1]
>>> sorted(inventory, key=getcount)
[('orange', 1), ('banana', 2), ('apple', 3), ('pear', 5)]

operator.methodcaller(name[, args...])
Return a callable object that calls the method name on its operand. If
additional arguments and/or keyword arguments are given, they will be given
to the method as well. After f = methodcaller('name'), the call f(b)
returns b.name(). After f = methodcaller('name', 'foo', bar=1), the
call f(b) returns b.name('foo', bar=1).
New in version 2.6.
Mapping Operators to Functions
This table shows how abstract operations correspond to operator symbols in the
Python syntax and the functions in the operator module.
Operation 
Syntax 
Function 
Addition 
a + b 
add(a, b) 
Concatenation 
seq1 + seq2 
concat(seq1, seq2) 
Containment Test 
obj in seq 
contains(seq, obj) 
Division 
a / b 
div(a, b) (without
__future__.division) 
Division 
a / b 
truediv(a, b) (with
__future__.division) 
Division 
a // b 
floordiv(a, b) 
Bitwise And 
a & b 
and_(a, b) 
Bitwise Exclusive Or 
a ^ b 
xor(a, b) 
Bitwise Inversion 
~ a 
invert(a) 
Bitwise Or 
a  b 
or_(a, b) 
Exponentiation 
a ** b 
pow(a, b) 
Identity 
a is b 
is_(a, b) 
Identity 
a is not b 
is_not(a, b) 
Indexed Assignment 
obj[k] = v 
setitem(obj, k, v) 
Indexed Deletion 
del obj[k] 
delitem(obj, k) 
Indexing 
obj[k] 
getitem(obj, k) 
Left Shift 
a << b 
lshift(a, b) 
Modulo 
a % b 
mod(a, b) 
Multiplication 
a * b 
mul(a, b) 
Negation (Arithmetic) 
 a 
neg(a) 
Negation (Logical) 
not a 
not_(a) 
Right Shift 
a >> b 
rshift(a, b) 
Sequence Repetition 
seq * i 
repeat(seq, i) 
Slice Assignment 
seq[i:j] = values 
setslice(seq, i, j, values) 
Slice Deletion 
del seq[i:j] 
delslice(seq, i, j) 
Slicing 
seq[i:j] 
getslice(seq, i, j) 
String Formatting 
s % obj 
mod(s, obj) 
Subtraction 
a  b 
sub(a, b) 
Truth Test 
obj 
truth(obj) 
Ordering 
a < b 
lt(a, b) 
Ordering 
a <= b 
le(a, b) 
Equality 
a == b 
eq(a, b) 
Difference 
a != b 
ne(a, b) 
Ordering 
a >= b 
ge(a, b) 
Ordering 
a > b 
gt(a, b) 
