[Python] Basic Syntax

Language Feature

Compared to Java Same:

1. Everything is an object design and excellent cross-platform support
2. Relatively standard libraries
3. Run on virtual machines, python does this automatically at runtime

Difference:

1. Python is strongly dynamically typed. Make it very easy to write and not hard to read.
2. A lot machine learning resources

Variables

Built-in Atomic Data Types int, float, bool.

Built-in Collection Data Types:

• Ordered Collection: list, string, tuple

• Integers in Python3 are unbounded

• Unlike integers, floats are not infinite precision, and it’s convenient to refer to infinite as float('inf') and float('-inf')
• Random methods random.randrange(28), random.randint(8,16), ranodm.random(), random.shuffle(A), random.choice(A)
• Unordered Collection: set, dictionary

Exception Handler

try:
    print(math.sqrt(anumber))
except:
    print("Bad Value for square root")

if anumber < 0:
    raise RuntimeError("You can't use a negative number") # Create more explicit error message
else:
    print(math.sqrt(anumber))

all and any

all(): checks if all the values in that iterable are non-False
any(): checks if any of the values in that iterable are non-False

Usage:

"""
Check if list1 contains all elements in list2
"""
result = all(elem in list1 for elem in list2)

"""
Check if list1 contains any of the elements in list2
"""
result = any(elem in list1 for elem in list2)

Efficiency

• list in python is much slower than set()
• xrange takes less space than range, because xrange returns an object and range returns a list