Python General Notes

***and       del       for       is        raiseassert    elif      from      lambda    returnbreak     else      global    not       tryclass     except    if        or        whilecontinue  exec      import    passdef       finally   in        print***

import math

def say_hi(name):"""<---- Multi-Line Comments and Docstrings
    This is where you put your content for help() to inform the user
    about what your function does and how to use it
    """print(f"Hello {name}!")print(say_hi("Bryan"))  # Should get the print inside the function, then None# Boolean Values# Work the same as in JS, except they are title case: True and False
a = True
b = False# Logical Operators# ! = not, || = or, && = andprint(True and True)print(True and not True)print(True or True)# Truthiness - Everything is True except...# False - None, False, '', [], (), set(), range(0)# Number Values# Integers are numbers without a floating decimal pointprint(type(3))  # type returns the type of whatever argument you pass in# Floating Point values are numbers with a floating decimal pointprint(type(3.5))# Type Casting# You can convert between ints and floats (along with other types...)print(float(3))  # If you convert a float to an int, it will truncate the decimalprint(int(4.5))print(type(str(3)))# Python does not automatically convert types like JS# print(17.0 + ' heyooo ' + 17)  # TypeError# Arithmetic Operators# ** - exponent (comparable to Math.pow(num, pow))# // - integer division# There is no ++ or -- in Python# String Values# We can use single quotes, double quotes, or f'' for string formats# We can use triple single quotes for multiline stringsprint("""This here's a story
All about how
My life got twist
Turned upside down
""")# Three double quotes can also be used, but we typically reserve these for# multi-line comments and function docstrings (refer to lines 6-9)(Nice :D)# We use len() to get the length of somethingprint(len("Bryan G"))  # 7 charactersprint(len(["hey", "ho", "hey", "hey", "ho"]))  # 5 list itemsprint(len({1, 2, 3, 4, 5, 6, 7, 9}))  # 8 set items# We can index into strings, list, etc..self.
name = "Bryan"for i in range(len(name)):print(name[i])  # B, r, y, a, n# We can index starting from the end as well, with negatives
occupation = "Full Stack Software Engineer"print(occupation[-3])  # e# We can also get ranges in the index with the [start:stop:step] syntaxprint(occupation[0:4:1])  # step and stop are optional, stop is exclusiveprint(occupation[::4])  # beginning to end, every 4th letterprint(occupation[4:14:2])  # Let's get weird with it!# NOTE: Indexing out of range will give you an IndexError# We can also get the index og things with the .index() method, similar to indexOf()print(occupation.index("Stack"))print(["Mike", "Barry", "Cole", "James", "Mark"].index("Cole"))# We can count how many times a substring/item appears in something as wellprint(occupation.count("S"))print("""Now this here's a story all about how
My life got twist turned upside down
I forget the rest but the the the potato
smells like the potato""".count("the"))# We concatenate the same as Javascript, but we can also multiply stringsprint("dog " + "show")print("ha" * 10)# We can use format for a multitude of things, from spaces to decimal places
first_name = "Bryan"
last_name = "Guner"print("Your name is {0} {1}".format(first_name, last_name))# Useful String Methodsprint("Hello".upper())  # HELLOprint("Hello".lower())  # helloprint("HELLO".islower())  # Falseprint("HELLO".isupper())  # Trueprint("Hello".startswith("he"))  # Falseprint("Hello".endswith("lo"))  # Trueprint("Hello There".split())  # [Hello, There]print("hello1".isalpha())  # False,  must consist only of lettersprint("hello1".isalnum())  # True, must consist of only letters and numbersprint("3215235123".isdecimal())  # True, must be all numbers# True, must consist of only spaces/tabs/newlinesprint("       \\n     ".isspace())# False, index 0 must be upper case and the rest lowerprint("Bryan Guner".istitle())print("Michael Lee".istitle())  # True!# Duck Typing - If it walks like a duck, and talks like a duck, it must be a duck# Assignment - All like JS, but there are no special keywords like let or const
a = 3
b = a
c = "heyoo"
b = ["reassignment", "is", "fine", "G!"]# Comparison Operators - Python uses the same equality operators as JS, but no ===# < - Less than# > - Greater than# <= - Less than or Equal# >= - Greater than or Equal# == - Equal to# != - Not equal to# is - Refers to exact same memory location# not - !# Precedence - Negative Signs(not) are applied first(part of each number)#            - Multiplication and Division(and) happen next#            - Addition and Subtraction(or) are the last step#  NOTE: Be careful when using not along with ==print(not a == b)  # True# print(a == not b) # Syntax Errorprint(a == (not b))  # This fixes it. Answer: False# Python does short-circuit evaluation# Assignment Operators - Mostly the same as JS except Python has **= and //= (int division)# Flow Control Statements - if, while, for# Note: Python smushes 'else if' into 'elif'!if 10 < 1:print("We don't get here")elif 10 < 5:print("Nor here...")else:print("Hey there!")# Looping over a stringfor c in "abcdefgh":print(c)# Looping over a rangefor i in range(5):print(i + 1)# Looping over a list
lst = [1, 2, 3, 4]for i in lst:print(i)# Looping over a dictionary
spam = {"color": "red", "age": 42, "items": [(1, "hey"), (2, "hooo!")]}for v in spam.values():print(v)# Loop over a list of tuples and destructuring the values# Assuming spam.items returns a list of tuples each containing two items (k, v)for k, v in spam.items():print(f"{k}: {v}")# While loops as long as the condition is True#  - Exit loop early with break#  - Exit iteration early with continue
spam = 0while True:print("Sike That's the wrong Numba")
    spam += 1if spam < 5:continuebreak# Functions - use def keyword to define a function in Pythondef printCopyright():print("Copyright 2021, Bgoonz")# Lambdas are one liners! (Should be at least, you can use parenthesis to disobey)def avg(num1, num2):return print(num1 + num2)

avg(1, 2)# Calling it with keyword arguments, order does not matter
avg(num2=20, num1=1252)
printCopyright()# We can give parameters default arguments like JSdef greeting(name, saying="Hello"):print(saying, name)

greeting("Mike")  # Hello Mike
greeting("Bryan", saying="Hello there...")# A common gotcha is using a mutable object for a default parameter# All invocations of the function reference the same mutable objectdef append_item(item_name, item_list=[]):  # Will it obey and give us a new list?
    item_list.append(item_name)return item_list

# Uses same item list unless otherwise stated which is counterintuitiveprint(append_item("notebook"))print(append_item("notebook"))print(append_item("notebook", []))# Errors - Unlike JS, if we pass the incorrect amount of arguments to a function,#          it will throw an error# avg(1)  # TypeError# avg(1, 2, 2) # TypeError# ----------------------------------- DAY 2 ----------------------------------------# Functions - * to get rest of position arguments as tuple#           - ** to get rest of keyword arguments as a dictionary# Variable Length positional argumentsdef add(a, b, *args):# args is a tuple of the rest of the arguments
    total = a + b
    for n in args:
        total += n
    return total

print(add(1, 2))  # args is None, returns 3print(add(1, 2, 3, 4, 5, 6))  # args is (3, 4, 5, 6), returns 21# Variable Length Keyword Argumentsdef print_names_and_countries(greeting, **kwargs):# kwargs is a dictionary of the rest of the keyword argumentsfor k, v in kwargs.items():print(greeting, k, "from", v)

print_names_and_countries("Hey there", Monica="Sweden", Mike="The United States", Mark="China")# We can combine all of these togetherdef example2(arg1, arg2, *args, kw_1="cheese", kw_2="horse", **kwargs):pass# Lists are mutable arrays
empty_list = []
roomates = ["Beau", "Delynn"]# List built-in function makes a list too
specials = list()# We can use 'in' to test if something is in the list, like 'includes' in JSprint(1 in [1, 2, 4])  # Trueprint(2 in [1, 3, 5])  # False# Dictionaries - Similar to JS POJO's or Map, containing key value pairs
a = {"one": 1, "two": 2, "three": 3}
b = dict(one=1, two=2, three=3)# Can use 'in' on dictionaries too (for keys)print("one" in a)  # Trueprint(3 in b)  # False# Sets - Just like JS, unordered collection of distinct objects
bedroom = {"bed", "tv", "computer", "clothes", "playstation 4"}# bedroom = set("bed", "tv", "computer", "clothes", "playstation 5")
school_bag = set(["book", "paper", "pencil", "pencil", "book", "book", "book", "eraser"])print(school_bag)print(bedroom)# We can use 'in' on sets as welprint(1 in {1, 2, 3})  # Trueprint(4 in {1, 3, 5})  # False# Tuples are immutable lists of items
time_blocks = ("AM", "PM")
colors = "red", "green", "blue"  # Parenthesis not needed but encouraged# The tuple built-in function can be used to convert things to tuplesprint(tuple("abc"))print(tuple([1, 2, 3]))# 'in' may be used on tuples as wellprint(1 in (1, 2, 3))  # Trueprint(5 in (1, 4, 3))  # False# Ranges are immutable lists of numbers, often used with for loops#   - start - default: 0, first number in sequence#   - stop - required, next number past last number in sequence#   - step - default: 1, difference between each number in sequence
range1 = range(5)  # [0,1,2,3,4]
range2 = range(1, 5)  # [1,2,3,4]
range3 = range(0, 25, 5)  # [0,5,10,15,20]
range4 = range(0)  # []for i in range1:print(i)# Built-in functions:# Filterdef isOdd(num):return num % 2 == 1

filtered = filter(isOdd, [1, 2, 3, 4])print(list(filtered))for num in filtered:print(f"first way: {num}")print("--" * 20)[print(f"list comprehension: {i}")for i in [1, 2, 3, 4, 5, 6, 7, 8] if i % 2 == 1]# Mapdef toUpper(str):return str.upper()

upperCased = map(toUpper, ["a", "b", "c", "d"])print(list(upperCased))# Sorted
sorted_items = sorted(["john", "tom", "sonny", "Mike"])print(list(sorted_items))  # Notice uppercase comes before lowercase# Using a key function to control the sorting and make it case insensitive
sorted_items = sorted(["john", "tom", "sonny", "Mike"], key=str.lower)print(sorted_items)# You can also reverse the sort
sorted_items = sorted(["john", "tom", "sonny", "Mike"],
                      key=str.lower, reverse=True)print(sorted_items)# Enumerate creates a tuple with an index for what you're enumerating
quarters = ["First", "Second", "Third", "Fourth"]print(list(enumerate(quarters)))print(list(enumerate(quarters, start=1)))# Zip takes list and combines them as key value pairs, or really however you need
keys = ("Name", "Email")
values = ("Buster", "cheetoh@johhnydepp.com")
zipped = zip(keys, values)print(list(zipped))# You can zip more than 2
x_coords = [0, 1, 2, 3, 4]
y_coords = [4, 6, 10, 9, 10]
z_coords = [20, 10, 5, 9, 1]
coords = zip(x_coords, y_coords, z_coords)print(list(coords))# Len reports the length of strings along with list and any other object data type# doing this to save myself some typingdef print_len(item):return print(len(item))

print_len("Mike")
print_len([1, 5, 2, 10, 3, 10])
print_len({1, 5, 10, 9, 10})  # 4 because there is a duplicate here (10)
print_len((1, 4, 10, 9, 20))# Max will return the max number in a given scenarioprint(max(1, 2, 35, 1012, 1))# Minprint(min(1, 5, 2, 10))print(min([1, 4, 7, 10]))# Sumprint(sum([1, 2, 4]))# Anyprint(any([True, False, False]))print(any([False, False, False]))# Allprint(all([True, True, False]))print(all([True, True, True]))# Dir returns all the attributes of an object including it's methods and dunder methods
user = {"Name": "Bob", "Email": "bob@bob.com"}print(dir(user))# Importing packages and modules#  - Module - A Python code in a file or directory#  - Package - A module which is a directory containing an __init__.py file#  - Submodule - A module which is contained within a package#  - Name - An exported function, class, or variable in a module# Unlike JS, modules export ALL names contained within them without any special export key# Assuming we have the following package with four submodules#  math#  |  __init__.py#  | addition.py#  | subtraction.py#  | multiplication.py#  | division.py# If we peek into the addition.py file we see there's an add function# addition.py# We can import 'add' from other places because it's a 'name' and is automatically exported# def add(num1, num2):#     return num1 + num2# Notice the . syntax because this package can import it's own submodules.# Our __init__.py has the following files# This imports the 'add' function# And now it's also re-exported in here as well# from .addition import add# These import and re-export the rest of the functions from the submodule# from .subtraction import subtract# from .division import divide# from .multiplication import multiply# So if we have a script.py and want to import add, we could do it many ways# This will load and execute the 'math/__init__.py' file and give# us an object with the exported names in 'math/__init__.py'# print(math.add(1,2))# This imports JUST the add from 'math/__init__.py'# from math import add# print(add(1, 2))# This skips importing from 'math/__init__.py' (although it still runs)# and imports directly from the addition.py file# from math.addition import add# This imports all the functions individually from 'math/__init__.py'# from math import add, subtract, multiply, divide# print(add(1, 2))# print(subtract(2, 1))# This imports 'add' renames it to 'add_some_numbers'# from math import add as add_some_numbers# --------------------------------------- DAY 3 ---------------------------------------# Classes, Methods, and Propertiesclass AngryBird:# Slots optimize property access and memory usage and prevent you# from arbitrarily assigning new properties the instance
    __slots__ = ["_x", "_y"]# Constructordef __init__(self, x=0, y=0):# Doc String"""
        Construct a new AngryBird by setting it's position to (0, 0)
        """# Instance Variables
        self._x = x
        self._y = y

    # Instance Methoddef move_up_by(self, delta):
        self._y += delta

    # Getter@propertydef x(self):return self._x

    # Setter@x.setterdef x(self, value):if value < 0:
            value = 0
        self._x = value

    @propertydef y(self):return self._y

    @y.setterdef y(self, value):
        self._y = value

    # Dunder Repr... called by 'print'def __repr__(self):return f"<AngryBird ({self._x}, {self._y})>"# JS to Python Classes cheat table#        JS                    Python#   constructor()         def __init__(self):#      super()            super().__init__()#   this.property           self.property#    this.method            self.method()# method(arg1, arg2){}    def method(self, arg1, ...)# get someProperty(){}    @property# set someProperty(){}    @someProperty.setter# List Comprehensions are a way to transform a list from one format to another#  - Pythonic Alternative to using map or filter#  - Syntax of a list comprehension#     - new_list = [value loop condition]# Using a for loop
squares = []for i in range(10):
    squares.append(i ** 2)print(squares)# value = i ** 2# loop = for i in range(10)
squares = [i ** 2 for i in range(10)]print(list(squares))
sentence = "the rocket came back from mars"
vowels = [character for character in sentence if character in "aeiou"]print(vowels)# You can also use them on dictionaries. We can use the items() method# for the dictionary to loop through it getting the keys and values out at once
person = {"name": "Corina", "age": 32, "height": 1.4}# This loops through and capitalizes the first letter of all keys
newPerson = {key.title(): value for key, value in person.items()}print(list(newPerson.items()))

 `def perm(l):                       # error: first line indented
for i in range(len(l)):             # error: not indented
    s = l[:i] + l[i+1:]
        p = perm(l[:i] + l[i+1:])   # error: unexpected indent
        for x in p:
                r.append(l[i:i+1] + x)
            return r                # error: inconsistent dedent`

def foo():
    """
    The foo function does many amazing things that you
    should not question. Just accept that it exists and
    use it with caution.
    """
    secretThing()

print(3) # => 3
print(int(19)) # => 19
print(int()) # => 0

print(2.24) # => 2.24
print(2.) # => 2.0
print(float()) # => 0.0
print(27e-5) # => 0.00027

print(7j) # => 7j
print(5.1+7.7j)) # => 5.1+7.7j
print(complex(3, 5)) # => 3+5j
print(complex(17)) # => 17+0j
print(complex()) # => 0j

# Using Float
print(17)               # => 17
print(float(17))        # => 17.0# Using Int
print(17.0)             # => 17.0
print(int(17.0))        # => 17# Using Str
print(str(17.0) + ' and ' + str(17))        # => 17.0 and 17

print('''My instructions are very long so to make them
more readable in the code I am putting them on
more than one line. I can even include "quotes"
of any kind because they won't get confused with
the end of the string!''')

print(len("Spaghetti")) # => 9

print("Spaghetti"[-1]) # => i print("Spaghetti"[-4]) # => e

print("Spaghetti"[1:4]) # => pag
print("Spaghetti"[4:-1]) # => hett
print("Spaghetti"[4:4]) # => (empty string)

# Shortcut to get from the beginning of a string to a certain index.
print("Spaghetti"[:4])  # => Spag
print("Spaghetti"[:-1])    # => Spaghett# Shortcut to get from a certain index to the end of a string.
print("Spaghetti"[1:])  # => paghetti
print("Spaghetti"[-4:])    # => etti

print("Spaghetti".index("h"))    # => 4
print("Spaghetti".index("t"))    # => 6

print("Spaghetti".count("h"))    # => 1
print("Spaghetti".count("t"))    # => 2
print("Spaghetti".count("s"))    # => 0
print('''We choose to go to the moon in this decade and do the other things,
not because they are easy, but because they are hard, because that goal will
serve to organize and measure the best of our energies and skills, because that
challenge is one that we are willing to accept, one we are unwilling to
postpone, and one which we intend to win, and the others, too.
'''.count('the '))                # => 4

first_name = "Billy"
last_name = "Bob"
print('Your name is {0} {1}'.format(first_name, last_name))  # => Your name is Billy Bob

a = 7
b = 'Marbles'
print(a)         # => 7
print(b)         # => Marbles

count = max = min = 0
print(count)           # => 0
print(max)             # => 0
print(min)             # => 0

a = 17
print(a)         # => 17
a = 'seventeen'
print(a)         # => seventeen

# Logical AND
print(True and True)    # => True
print(True and False)   # => False
print(False and False)  # => False# Logical OR
print(True or True)     # => True
print(True or False)    # => True
print(False or False)   # => False# Logical NOT
print(not True)             # => False
print(not False and True)   # => True
print(not True or False)    # => False

print (2 == '2')    # => False
print (2 is '2')    # => Falseprint ("2" == '2')    # => True
print ("2" is '2')    # => True# There is a distinction between the number types.
print (2 == 2.0)    # => True
print (2 is 2.0)    # => False

spam = 0
while spam < 5:
  print('Hello, world.')
  spam = spam + 1

spam = 0
while True:
  print('Hello, world.')
  spam = spam + 1
  if spam >= 5:
    break

spam = 0
while True:
  print('Hello, world.')
  spam = spam + 1
  if spam < 5:
    continue
  break

a = 321
try:
    print(len(a))
except:
    print('Silently handle error here')    # Optionally include a correction to the issue
    a = str(a)
    print(len(a)a = '321'
try:
    print(len(a))
except:
    print('Silently handle error here')    # Optionally include a correction to the issue
    a = str(a)
    print(len(a))

a = 100
b = 0
try:
    c = a / b
except ZeroDivisionError:
    c = None
print(c)

a = 100
b = 0
try:
    print(a / b)
except ZeroDivisionError:
    pass

a = 100
# b = "5"
try:
    print(a / b)
except ZeroDivisionError:
    pass
except (TypeError, NameError):
    print("ERROR!")

# tuple of file names
files = ('one.txt', 'two.txt', 'three.txt')# simple loop
for filename in files:
    try:
        # open the file in read mode
        f = open(filename, 'r')
    except OSError:
        # handle the case where file does not exist or permission is denied
        print('cannot open file', filename)
    else:
        # do stuff with the file object (f)
        print(filename, 'opened successfully')
        print('found', len(f.readlines()), 'lines')
        f.close()

def divide(x, y):
    try:
        result = x / y
    except ZeroDivisionError:
        print("Cannot divide by zero")
    else:
        print("Result is", result)
    finally:
        print("Finally...")

# Try a number - nothing will print out
a = 321
if hasattr(a, '__len__'):
    print(len(a))# Try a string - the length will print out (4 in this case)
b = "5555"
if hasattr(b, '__len__'):
    print(len(b))

if (true) {
}while (true) {}if True:
  passwhile True:
  pass

def greeting(name, saying="Hello"):
    print(saying, name)greeting("Monica")
# Hello Monicagreeting("Barry", "Hey")
# Hey Barry

# THIS IS BAD CODE AND WILL NOT RUN
def increment(delta=1, value):
    return delta + value

def greeting(name, saying="Hello"):
    print(saying, name)# name has no default value, so just provide the value
# saying has a default value, so use a keyword argument
greeting("Monica", saying="Hi")

shopping_list = ['bread','milk','eggs']
print(','.join(shopping_list))

print('{:,}'.format(1234567890))
'1,234,567,890'

d = datetime.datetime(2020, 7, 4, 12, 15, 58)
print('{:%Y-%m-%d %H:%M:%S}'.format(d))
'2020-07-04 12:15:58'

points = 190
total = 220
print('Correct answers: {:.2%}'.format(points/total))
Correct answers: 86.36%

width=8
print(' decimal hex binary')
print('-'*27)
for num in range(1,16):
for base in 'dXb':
print('{0:{width}{base}}'.format(num, base=base, width=width), end=' ')
print()
Getting Input from the Command Line
Python runs synchronously, all programs and processes will stop when listening for a user input.
The input function shows a prompt to a user and waits for them to type 'ENTER'.
Scripts vs Programs
Programming Script : A set of code that runs in a linear fashion.
The largest difference between scripts and programs is the level of complexity and purpose. Programs typically have many UI's.

empty_list = []
departments = ['HR','Development','Sales','Finance','IT','Customer Support']

specials = list()

print(1 in [1, 2, 3]) #> True
print(4 in [1, 2, 3]) #> False
# Tuples : Very similar to lists, but they are immutable

time_blocks = ('AM','PM')

colors = 'red','blue','green'
numbers = 1, 2, 3

tuple('abc') # returns ('a', 'b', 'c')
tuple([1,2,3]) # returns (1, 2, 3)
# Think of tuples as constant variables.

range(5) # [0, 1, 2, 3, 4]range(1,5) # [1, 2, 3, 4]range(0, 25, 5) # [0, 5, 10, 15, 20]range(0) # [ ]for let (i = 0; i < 5; i++)for let (i = 1; i < 5; i++)for let (i = 0; i < 25; i+=5)for let(i = 0; i = 0; i++)# Keep in mind that stop is not included in the range.

a = {'one':1, 'two':2, 'three':3}
b = dict(one=1, two=2, three=3)
c = dict([('two', 2), ('one', 1), ('three', 3)])
# a, b, and c are all equal

school_bag = {'book','paper','pencil','pencil','book','book','book','eraser'}
print(school_bag)

letters = set('abracadabra')
print(letters)
#Built-In Functions
#Functions using iterables

quarters = ['First', 'Second', 'Third', 'Fourth']
print(enumerate(quarters))
print(enumerate(quarters, start=1))

a = {1, 2, 3}
b = {2, 4, 6}
print(a | b) # => {1, 2, 3, 4, 6}

a = {1, 2, 3}
b = {2, 4, 6}
print(a & b) # => {2}
Difference : The — operator can be used to produce a new set of only the elements that appear in the first set and NOT the others.

a = {1, 2, 3}
b = {2, 4, 6}print(a — b) # => {1, 3}print(b — a) # => {4, 6}print(a ^ b) # => {1, 3, 4, 6}

print('My name is')for i in range(5):print('Carlita Cinco (' + str(i) + ')')total = 0for num in range(101):
total += num
print(total)
Looping over a list in Python
for c in ['a', 'b', 'c']:print(c)lst = [0, 1, 2, 3]for i in lst:print(i)

supplies = ['pens', 'staplers', 'flame-throwers', 'binders']for i in range(len(supplies)):print('Index ' + str(i) + ' in supplies is: ' + supplies[i])

l = 1, 2], [3, 4], [5, 6
for a, b in l:
print(a, ', ', b)

spam = {'color': 'red', 'age': 42}
for v in spam.values():
print(v)

for k in spam.keys():
print(k)

for i in spam.items():
print(i)

for k, v in spam.items():
print('Key: ' + k + ' Value: ' + str(v))

for c in "abcdefg":
print(c)

def example(arg_1, arg_2, *args, **kwargs):
passdef example2(arg_1, arg_2, *args, kw_1="shark", kw_2="blowfish", **kwargs):
pass

from urllib.request import (
HTTPDefaultErrorHandler as ErrorHandler,
HTTPRedirectHandler as RedirectHandler,
Request,
pathname2url,
url2pathname,
urlopen,
)