Which operator is equivalent to different in Python?

Question

I know some other operators:

• Greater than: >
• Less than: <
• Equality: ==

But the "different" operator, as it is in Python?

Answer 1

As with most languages, the difference operator in Python is !=. Remember that it compares only the value between the operands and not their identities.

a = 2
b = 3

if a != b:
    print('a é diferente de b')
else:
    print('a é igual a b')

In advance, the operator != implicitly invokes the method __ne__ of the first operand, passing the second as parameter, so if you need to override such operator in a class, you can do:

class Foo:
    def __init__(self, value):
        self.value = value

    def __ne__(self, other):
        return self.value != other.value

f1 = Foo(1)
f2 = Foo(1)

print(f1 != f2)  # False

Without overloading the method, the result would be True, indicating that the objects are different, even though they appear to be the same.

---

The operator is (or is not) checks the identity of objects and not only their values. This is evident, for now, when worked with changeable types:

a = [1]
b = [1]

print(a != b)  # False
print(a is not b)  # True

The lists a and b have the same value, but are not the same object.

Additional readings

• In Python, what are the consequences of using is instead of '=='
• In Python, what is the difference between == and the command is?

---

Other existing operators in the language are:

• Addition, a + b, when a and b are numerical;

  >>> 1 + 2
  3
  

• Concatenation, a + b, when a and b are sequences;

  >>> 'Anderson' + ' ' + 'Woss'
  'Anderson Woss'
  >>> [1, 2] + [3, 4]
  [1, 2, 3, 4]
  

• Containment, a in b;

  >>> 1 in [1, 2, 3, 4]
  True
  

• True division, a / b, which returns the actual result;

  >>> 5/2
  2.5
  

• Division with truncation, a // b, that returns only the entire part;

  >>> 5//2
  2
  

• And binary, a & b;

  >>> 1 & 3
  1
  

• OR binary exclusive, a ^ b;

  >>> 1 ^ 2
  3
  

• Binary inversion, ~a;

  >>> ~2
  -3
  

• OR binary, a | b;

  >>> 1 | 2
  3
  

• Exponentiation, a**b;

  >>> 2**10
  1024
  

• Identity, a is b;

  >>> 1 is None
  False
  

• Identity, a is not b;

  >>> 1 is not None
  True
  

• Indexing, obj[k];

  >>> obj = [1, 2, 3]
  >>> obj[1]
  2
  

• Index assignment, obj[k] = v;

  >>> obj = [1, 2, 3]
  >>> obj[2] = 4
  >>> obj
  [1, 2, 4]
  

• Exclusion by index, del obj[k];

  >>> obj = [1, 2, 3]
  >>> del obj[1]
  >>> obj
  [1, 3]
  

• Torque displacement to left, a << b;

  >>> 4 << 1
  8
  

• Right torque displacement, a >> b;

  >>> 4 >> 1
  2
  

• Division rest, a % b;

  >>> 5 % 2
  1
  

• Multiplication, a * b;

  >>> 2 * 3
  6
  

• Matrix multiplication, a @ b (versions 3.5+);

  See PEP 465;

• Arithmetic negation, -a;

  >>> -4
  -4
  

• Logical denial, not a;

  >>> not True
  False
  

• Positive, +a;

  >>> +4
  4
  

• Slicing, seq[i:j];

  >>> obj = [1, 2, 3, 4, 5]
  >>> obj[1:3]
  [2, 3]
  

• Slice assignment, seq[i:j] = values;

  >>> obj = [1, 2, 3, 4, 5]
  >>> obj[1:3] = [8, 9]
  >>> obj
  [1, 8, 9, 4, 5]
  

• Foreclosure, del seq[i:j];

  >>> obj = [1, 2, 3, 4, 5]
  >>> del obj[1:3]
  >>> obj
  [1, 4, 5]
  

• Formatting of string, s % obj (prefer method format or f-strings);

  >>> 'Olá, %s' % 'mundo'
  'Olá, mundo'
  

• Subtraction, a - b;

  >>> 3 - 1
  2
  

• Test of truth, if obj: ...;

  >>> obj = 3
  >>> if obj: print('Ok')
  'Ok'
  

• Less than, a < b;

  >>> 1 < 2
  True
  

• Less than or equal to, a <= b;

  >>> 1 <= 2
  True
  

• Greater than, a > b;

  >>> 1 > 2
  False
  

• Greater than or equal to, a >= b;

  >>> 1 >= 2
  False
  

• Enter, not including, a < v < b;

  >>> v = 5
  >>> 1 < v < 9
  True
  

• Between, inclusive, a <= v <= b;

  >>> v = 5
  >>> 1 <= v <= 9
  True
  

• Equality, a == b;

  >>> 1 == 2
  False
  

• Difference, a != b;

  >>> 1 != 2
  True
  

• Difference, a <> b (obsolete as of version 2.5, removed in versions 3+);

  >>> 1 <> 2
  True
  

Further information can be found on official documentation.

Answer 2

In Python you could use Different "!=" or Not "is not"

if "Foo" != "Bar":
    return "Diferente"

if "Foo" is not "Bar":
    return "Diferente"