Wednesday, 5 July 2017

Python 101 - Part 1



PEP


Python Enhancements Proposal (guidelines)
PEP 8: Style Guide For Python Code
PEP 20: Zen of Python


Indentation


Used to mark blocks, curly braces no longer needed
Recommendation is to use 4 spaces for indentation, be consistent and not to mix spaces with tabs


Modules


- Use modules available in Python

e.g.: import math

After importing use the module name to call functions:

math.sqrt(5)
math.factorial(5)

from math import factorial -> factorial(5) # avoid using math
from math import factorial as fac -> fac(5) #shorter name


Help (in REPL cmd)


- Get help on a module
help(math)

- Get help on a function
help(math.sqrt)
help(math.factorial)


int, float


int(10), int(10.2), int(“10”)

float(10), float(10.2), float(“10.2”)


Nan,inf

float(“nan”) # not a number
float(“inf”) # infinity


None


Represents absence of value

a = None
a Is None # returns True


Boolean


0: falsy
Non-zero (inc. negative): truthy

bool(0) bool(0.0): # False
bool(-1) # True

For Lists

If list is empty: bool(list) returns False

bool([]) # False
bool([1,2,3]) # True

For strings:

bool(“”) # False
bool(“a”) # True
bool(“      “) # all white spaces, True

if “ihavesomething”:  # this is True
    print(“this is True”)


Raw strings



path = r’C:\Users\Documents\Course’

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