Python Programming for Biology: Bioinformatics and Beyond

greater or equal in value than the second,

giving True if it is and False otherwise.

x = 2**10

x >= 1024

Evaluates to True.

<=

Tests whether the value of the first operand is

smaller or equal in value than the second,

giving True if it is and False otherwise.

x = 2**10

x <= 512

Evaluates to False.

is

Tests whether two operands represent the same

Python object, giving True if they do and False

otherwise.

x = True

if x is True:

print("Success")

is not

Tests whether two operands represent different

Python objects, giving True if they are different

and False if they are the same.

value =

myDict.get(key)

if value is not

None:

print('Found

key')

Binary operators

The following are standard bitwise binary operations that are built into Python.

Operator

Description

Example

x & y

The bitwise binary AND operation, giving 1 if

both bits at a position are 1, and 0 otherwise.

x = 0b11111000

y = 0b10011111

print(bin(x & y))

Result is

0b10011000.

x | y

The bitwise binary OR operation, giving 1 if

any of the bits at a position are 1, and 0

otherwise.

x = 0b11010000

y = 0b00001101

print(bin(x | y))

Result is

0b11011101.

x ^ y

The bitwise binary XOR operation, giving 1

only if one of the bits, but not both, at a

position is 1, and 0 otherwise.

x = 0b11111000

y = 0b00011111

print(bin(x ^ y))

Result is

---

0b11100111.

x << n

The left-shift bit operation. Moves the bits of

x by n places to the left. The same as

multiplying x by 2**n.

x = 0b00010101 #

21 in decimal

print(bin(x << 2))

Result is

0b1010100; 84 in

decimal.

x >> n

The right-shift bit operation. Moves the bits of

x by n places to the right. The same as the

integer part of dividing x by 2**n.

x = 0b01010101 #

85 in decimal

print(bin(x >> 1))

Result is 0b101010;

42 in decimal.

~x

The bitwise binary NOT operation; forms the

complementary binary number by flipping 1

for 0 and 0 for 1. Note this flips all bits in the

full binary representation whether they are

directly represented or not (i.e. have implicit

leading zeros).

from numpy import

int8

x =

int8(0b11000011)

print(bin(~x))

Result is 0b111100.

Note use of 8-bit

integers from

NumPy to avoid

implicit zeros in

normal Python

integers.