Questions to David Rotermund
Number is Python
In Python everything is a class. Numbers are classes as well.
Integer
a_number = 0
print(type(a_number)) # -> <class 'int'>
FLOATing point number
a_second_number = 3.33
print(type(a_second_number)) # -> <class 'float'>
Conversion (i.e. casts) between types
a_second_number = 3.33
a_second_number = int(a_second_number)
print(type(a_second_number)) # -> <class 'int'>
Order of operations: 1. Parentheses 2. Exponents 3. Multiplication/Division 4. Addition/Subtraction
| Operator
|
Description
|
| x + y
|
sum of x and y
|
| x - y
|
difference of x and y
|
| x * y
|
product of x and y
|
| x / y
|
quotient of x and y
|
| x // y
|
floored quotient of x and y
|
| x % y
|
remainder of x / y
|
| -x
|
x negated
|
| +x
|
x unchanged
|
| Operator
|
Description
|
| abs(x)
|
absolute value or magnitude of x
|
| int(x)
|
x converted to integer
|
| float(x)
|
x converted to floating point
|
| complex(re, im)
|
a complex number with real part re, imaginary part im. im defaults to zero.
|
| c.conjugate()
|
conjugate of the complex number c
|
| divmod(x, y)
|
the pair (x // y, x % y)
|
| pow(x, y)
|
x to the power y
|
| x ** y
|
x to the power y
|
“True division”
print(5 / 2) # -> 2.5
print(6 / 2) # -> 3.0
“Floor division”
print(5 // 2) # -> 2
print(6 // 2) # -> 3
Inplace Operation
| Inplace Operation
|
Short for
|
| a += b
|
a = a + b
|
| a &= b
|
a = a & b
|
| a //= b
|
a = a // b
|
| a <<= b
|
a = a << b
|
| a %= b
|
a = a % b
|
| a *= b
|
a = a * b
|
| a @= b
|
a = a @ b
|
| = b
|
b
|
| a **= b
|
a = a ** b
|
| a >>= b
|
a = a >> b
|
| a -= b
|
a = a - b
|
| a /= b
|
a = a / b
|
| a ^= b
|
a = a ^ b
|
| Operation
|
Result
|
| x or y
|
if x is false, then y, else x
|
| x and y
|
if x is false, then x, else y
|
| not x
|
if x is false, then True, else False
|
| Operation
|
Meaning
|
| <
|
strictly less than
|
| <=
|
less than or equal
|
| >
|
strictly greater than
|
| >=
|
greater than or equal
|
| ==
|
equal
|
| !=
|
not equal
|
| is
|
object identity
|
| is not
|
negated object identity
|
| Operation
|
Result
|
| y
|
bitwise or of x and y
|
| x ^ y
|
bitwise exclusive or of x and y
|
| x & y
|
bitwise and of x and y
|
| x << n
|
x shifted left by n bits
|
| x >> n
|
x shifted right by n bits
|
| ~x
|
the bits of x inverted
|
You need to include the math lib for that! (Only once per .py file and in the beginning of the file)
However, don’t get used to it. As a data scientist you will not use it. You will use Numpy.
import math
print(math.cos(math.pi))
Examples
| Number-theoretic and representation functions
|
| math.ceil(x)
|
| math.comb(n, k)
|
| math.fabs(x)
|
| math.factorial(n)
|
| math.floor(x)
|
| math.fmod(x, y)
|
| math.fsum(iterable)
|
| math.isclose(a, b, *, rel_tol=1e-09, abs_tol=0.0)
|
| math.isfinite(x)
|
| math.isinf(x)
|
| math.isnan(x)
|
| math.perm(n, k=None)
|
| math.prod(iterable, *, start=1)
|
| math.trunc(x)
|
| Power and logarithmic functions
|
| math.cbrt(x)
|
| math.exp(x)
|
| math.exp2(x)
|
| math.expm1(x)
|
| math.log(x[,base])
|
| math.log1p(x)
|
| math.log2(x)
|
| math.log10(x)
|
| math.pow(x, y)
|
| math.sqrt(x)
|
| Trigonometric functions
|
| math.acos(x)
|
| math.asin(x)
|
| math.atan(x)
|
| math.atan2(y, x)
|
| math.cos(x)
|
| math.sin(x)
|
| math.tan(x)
|
| math.dist(p, q)
|
| Hyperbolic functions
|
| math.acosh(x)
|
| math.asinh(x)
|
| math.atanh(x)
|
| math.cosh(x)
|
| math.sinh(x)
|
| math.tanh(x)
|
This is an optional topic!
If you do a + b, in reality this is internally replaced by add(a, b).
These are the “Mapping Operators to Functions”:
| 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
|
truediv(a, b)
|
| 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
|
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)
|
| Matrix Multiplication
|
a @ b
|
matmul(a, b)
|
| Negation (Arithmetic)
|
- a
|
neg(a)
|
| Negation (Logical)
|
not a
|
not_(a)
|
| Positive
|
+ a
|
pos(a)
|
| Right Shift
|
a >> b
|
rshift(a, b)
|
| Slice Assignment
|
seq[i:j] = values
|
setitem(seq, slice(i, j), values)
|
| Slice Deletion
|
del seq[i:j]
|
delitem(seq, slice(i, j))
|
| Slicing
|
seq[i:j]
|
getitem(seq, slice(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)
|
In-place Operators
| a += b
|
a = iadd(a, b)
|
| a &= b
|
a = iand(a, b)
|
| a += b for a and b sequences
|
a = iconcat(a, b)
|
| a //= b
|
a = ifloordiv(a, b)
|
| a <<= b
|
a = ilshift(a, b)
|
| a %= b
|
a = imod(a, b)
|
| a *= b
|
a = imul(a, b)
|
| a @= b
|
a = imatmul(a, b)
|
| = b
|
a = ior(a, b)
|
| a **= b
|
a = ipow(a, b)
|
| a >>= b
|
a = irshift(a, b)
|
| a -= b
|
a = isub(a, b)
|
| a /= b
|
a = itruediv(a, b)
|
| a ^= b
|
a = ixor(a, b)
|
