Awesome Python Tricks

list1 = []
bool(list1) # prints False
list2 = [10, 20, 30]
bool(list2) # prints True

#None means no value while an empty list means zero values.
#Semantically, they are different.

print (os.path.basename("/path/to/file.txt"))
# file.txt

assert("python" == "java", 'Assert Failed')
# This will always be true and will never fail.
# Following is the right way of doing it" 
assert "python" == "java", 'Assert Failed'

_var # Preferred convention for internal variables and methods
var_ # Used to avoid naming conflicts with Python keywords
__var # Used for [name mangling](https://dbader.org/blog/meaning-of-underscores-in-python) by Python when used in class context
    # Python interpreter changes the name of the variable to avoid collision with child class
__var__ # Reserved for special use in the language
 - # Used as a temporary or don't care varaibles

The Zen of Python, by Tim Peters

Beautiful is better than ugly.
Explicit is better than implicit.
Simple is better than complex.
Complex is better than complicated.
Flat is better than nested.
Sparse is better than dense.
Readability counts.
Special cases aren't special enough to break the rules.
Although practicality beats purity.
Errors should never pass silently.
Unless explicitly silenced.
In the face of ambiguity, refuse the temptation to guess.
There should be one-- and preferably only one --obvious way to do it.
Although that way may not be obvious at first unless you're Dutch.
Now is better than never.
Although never is often better than *right* now.
If the implementation is hard to explain, it's a bad idea.
If the implementation is easy to explain, it may be a good idea.
Namespaces are one honking great idea -- let's do more of those!

lst = list()
print(dir(lst))
# ['__add__', '__class__', '__contains__', '__delattr__', ..., 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort']

number = 123
print(dir(number))
# ['__abs__', '__add__', '__and__', '__bool__', '__ceil__', ..., 'from_bytes', 'imag', 'numerator', 'real', 'to_bytes']

str = "This is a String"
print(dir(str))
# ['__add__', '__class__', '__contains__', '__delattr__', ..., 'title', 'translate', 'upper', 'zfill']

def my_name():
...     return "Akash"
...

>>> dis.dis(my_name)
  2           0 LOAD_CONST               1 ('Akash')
 
3 RETURN_VALUE 


>>> def my_name():
...     print("Akash")
...
>>> dis.dis(my_name)
  2           0 LOAD_CONST               1 ('Akash')
              3 PRINT_ITEM
              4 PRINT_NEWLINE
              5 LOAD_CONST               0 (None)
              8 RETURN_VALUE

def map2(func, iter):
    for val in iter:
        yield func(val)

# The above method can be used as bellow similar to `map` function
lst = list(map2(str.upper, ['Save Earth', 'Save Animals', 'Save water']))
print(lst)
#['SAVE EARTH', 'SAVE ANIMALS', 'SAVE WATER']

import csv

with open( <path-to-file>, 'r' ) as theFile:
    reader = csv.DictReader(theFile)
    for line in reader:
        # line is { 'house_name': 'Houstan', 'price': 7.334, 'age': 5, ... }
        print (line)

namelist = ["Avish", "Piyush", "Tom"]
agelist = [17, 22, 38]

for name, age in zip(namelist, agelist):
    print(name, age)