^^Arithmetic. Operators. Python.

Assegnazione

1. x = y = z = 0  # A value can be assigned to several variables simultaneously.
2. a , b = 5 , 7    # multiple assignment
3. Mixed integer and floating point, convert to float

In-place operators. Infix notation.

%  percentage sign for integer remainder

**  Double star for exponentiation
      Attenzione:  "^"  e' Bitwise XOR, non esponenziazione come in Basic

/    divisione con virgola, cioe' quoziente

//   floor division, il risultato ha tipo intero

Operazione e assegnazione. Augmented assignment.

For mutable objects like lists, arrays, or DataFrames, these augmented assignment operations are actually subtly different than their more verbose counterparts: they modify the contents of the original object rather than creating a new object to store the result.

Comparison (operators)

=    single  is assignment,

==   double is comparison

1 < 3 < 5 unlike most programming languages, Python allows inequalities to be chained together, just as in mathematics.

Boolean logic.  Operator    and  or  not

a XOR b    equi    a != b

Identity Operators: "is" and "is not"

check for object identity.

Object identity is different than equality !

a = [1, 2, 3]
b = [1, 2, 3]

c = b

a == b

 True

a is b

 False

c is b

 True

Membership operators:  "in"  "not in"

check for membership within compound objects.

2 in [1, 2, 3]

 True

2 not in [1, 2, 3]

 False

Python  VS   lower-level languages such as C

Python easy to use, es membership operators

• in C, membership determined by manually constructing a loop over the list and checking for equality of each value
• n Python, you just type what you want to know, in a manner reminiscent of straightforward English prose.

carleton.ca/paulogarcia/how-to-confront-programming-languages

Conditional espression. Ternary operator.

1. reference/conditional-expressions (sometimes called a “ternary operator”) have the lowest priority of all Python operations.

   The expression   x if C else y 
   first evaluates the condition, C rather than x. If C is true, x is evaluated and its value is returned; otherwise, y is evaluated and its value is returned

2. Storia
   1. What’s New in Python 2.5 PEP 308: Conditional Expressions
   2. PEP 308 - Conditional Expressions. PEP written by Guido van Rossum and Raymond D. Hettinger; implemented by Thomas Wouters.