Learning Data Science

print("Hello World")

print("Hello World")

print(type(5))
print(type(5.5))
print(type(True))
print(type('hello'))
print(type(None))

print("Hello World")
print("4.5")           # looks like a float but is a string
print(Hello World)     # -> gives an error, not in quotes
print(4.5)             # is OK
print(4.4, "hello")    # is OK, automatically add spaces

print("Hello\nFriend")  # \n is the 'newline' character

# example
print("Hello", 55, True)

# use comma and space instead of just space
print("Hello", 55, True, sep=", ")

 # default end is \n
print("Hello", 55, True, sep=", ", end="\n") 

# Here we set the end to be nothing
# No newline is printed between these two
print("Hello", 55, True, end="")
print("Hello", 55, True)

word = 'hello'

print(word)

# will print 'hello'

word = 'hello'
last_word = 'world'

print(word, last_word)

# 'hello world'

word = 'bye bye'

print(word, last_word)
# 'bye bye world'

✅ variable = 1
✅ special_variable = 1
✅ variable1 = 1


❌ 1variable = 1
❌ special variable = 1
❌ spet❌l_variable = 1

⚠️ specialVariable = 1
# allowed but not 'pythonic'

input("Name: ")

# we put the space after to create buffer between the text and the user input

name = input("Name: ")

print('Hello', name)

age = input("Your age: ")

age = float(age)

# OR do it all at once
age = float(input("Your age: "))

word = "hello"

word.upper()

word = "hello"

print(word.upper())
# HELLO

# OR
word = "hello".upper()
print(word)
# SAME THING!

word = 'HeLLO'
print(word.lower())
# hello

word = 'hEllO'
print(word.capitalize())
# Hello

word = 'hello'
print(word.replace('h', 'H'))
# Hello

word = 'HELLO WORLD'
print(word.count('ll'))
# 0 
# (there are no 
# lower case Ls)

# first convert the 
# whole thing to lowercase
# can chain methods
print(word.lower().count('ll'))  
# 2

word = "hello"
y = 3

print(word * y)
# hellohellohello

x = "hello"
y = "world"

print(x + y)
# helloworld

name = "Susie"
age = 3

print(f"{name} is {age} years old")
# Susie is 3 years old

name = "Susie"
age = 3

print(f"{name.upper()} is {age+20} years old")
# SUSIE is 23 years old

x = 'hello'
y = 'hello'

print(x == y)
# True

print(x != y)
# False

y = 'Hello'

print(x == y)
# False

x = 'hello'
y = 'hello'

print(x == y)
# True

print(x != y)
# False

y = 'Hello'

print(x == y)
# False

print(2 > 1)
# True

print(2 == 2.0)
# True

result = 4 == 4
print(result)
# True

result = 4 == 3
print(result)
# False

x = 3
y = 4

result1 = x == y
result2 = y > x
result3 = x**2 > y

print(result1, result2, result3)
# False True True

# OR
print(True or False)
print(result1 or result2)
# True
# True

# NOT
print(not True)
print(result2, not result2)
print(result1 or not result2)
# False
# True False
# False

# AND
print(True and False)
print(result1 and result2)
print(result2 and result3)
# False
# False
# True

age = 20
is_adult = age > 18
was_child_five_years_ago = age - 5 < 18

print(is_adult and was_child_five_years_ago)

x = 4
y = 8
z = 3

a = x != z
b = z**2 > y
c = z**2 - y == 0

# 1
print(a and b and not c)

# 2
print(not a or not b or c)

# 3
print(not (a and b))

x = float(input("Enter a number: "))

if x > 0:
    print("x is positive")

print("thanks for playing!")

x = float(input("Enter a number: "))

if x > 0:
    print("x is positive")

print("thanks for playing!")

x = float(input("Enter a number: "))

if x > 0:
    print("x is positive")
else:
    print("x is negative")

print("thanks for playing!")
    

x = float(input("Enter a number: "))

if x > 0:
    print("x is positive")
elif x == 0:
    print("x is zero, you are clever!")
else:
    print("x is negative")

print("thanks for playing!")
    

x = float(input("Enter a number: "))

if x > 0:
    print("x is positive")
elif x == 0:
    pass
else:
    print("x is negative")

print("thanks for playing!")
    

x = float(input("Enter a number: "))

# note we need to rearrange!!!

if x > 0:
    print("x is positive")
elif x == 0:
    print("x is zero, you are clever!")
elif x == 42:
    print("x is the answer to the universe!")
else:
    print("x is negative")

print("thanks for playing!")
    

x = input("Please enter your favorite color: ")

if x == 'red':
    print("That is a warm color!")
elif x == 'blue':
    print("That is a cool color!")
elif x == 'green':
    print("That is also my favorite color!")
elif x == 'gold':
    print("You are rich!")
elif x == 'black':
    print("Go to Berlin.")
elif x == 'purple':
    print("That is a nice color!")
elif x == 'orange':
    print("That is a fruit!")
elif x == 'yellow':
    print("That is a choice!")
elif x == 'pink':
    print("That is a strawberry!")
else:
    print("I don't know that color")

x = input("Please enter your favorite color: ")

match x:
    case 'red':
        print("That is a warm color!")
    case 'blue':
        print("That is a cool color!")
    case 'green':
        print("That is also my favorite color!")
    case 'gold':
        print("You are rich!")
    case 'black' | 'silver':
        print("Go to Berlin.")
    case _:
        print("I don't know that color")

x = input("Please enter your favorite color: ")

match x:
    case 'red':
        print("That is a warm color!")
    case 'blue':
        print("That is a cool color!")
    case 'green':
        print("That is also my favorite color!")
    case 'gold':
        print("You are rich!")
    case 'black' | 'silver':
        print("Go to Berlin.")
    case _:
        print("I don't know that color")

# square brackets to make a list
x = [1, 2, 3]

# you can check the length
print(len(x))

# you can add items to the end with append
x.append(4)
print(x)

print(len(x))

x = [1, 2, 3]

x.extend([4, 5, 6])
print(x)

# indexing in list
# start counting at 0

x = ['hello', 'world', 'how', 'are', 'you']

print(x[0])
print(x[1])
print(x[2])
print(x[3])
print(x[4])

# negative indexing
print(x[-1])
print(x[-2])
print(x[-3])
print(x[-4])

x = [1, 'friend', 3.5, True]

print(x[1])

# set the value of an item in the list
x[1] = 'best'
print(x)

# removing last item from list

x = [1, 2, 3, 4, 5]
print(x.pop())
print(x)

print(x.pop(0))
print(x)

# nested lists
x = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

print(x[0])
print(x[2][1])

# can also rewrite to read it more clearly
x = [
    [1, 2, 3], 
    [4, 5, 6], 
    [7, 8, 9]
]

# nested lists
x = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]

print(x[0])
print(x[2][1])

# can also rewrite to read it more clearly
x = [
    [1, 2, 3], 
    [4, 5, 6], 
    [7, 8, 9]
]

# tuples are immutable
# to change, you need to simply create a new tuple
x = (1, 2, 3)

print(x[0])

x[0] = 4
# raises and error, you cannot edit!

x = [1, 2, 3, 4, 5]

print(1 in x)

if 3 in x:
    print("3 is in the list")
else:
    print("3 is not in the list")
    
if 6 not in x:
    print("6 is not in the list")

x = [1, 2, 3, 4, 5]

for i in x:
    print(i)

# it also works with a tuple!
x = (1, 2, 3, 4, 5)

for i in x:
    print(i)

# strings are also iterable!
for letter in 'Hello World':
    print(letter)

for num in range(10):
    print(num)
    
# range(start, stop, step)
# default (start=0, step=1)

# Go from 0 to 10, but only
# every two numbers
for num in range(10, step=2):
    print(num)
    
# Can go backwards with negative step
for num in range(10, -1, -1):
    print(num)
# Go from 10 to -1, stepping down -1
# each time

names = ["Susie", "Jenny", "Tim"]
fruits = ["bananas", "oranges", "avocados"]

for name in names:
    for fruit in fruits:
        print(f"{name} eats {fruit}. Yum!")
    print("---")

x = ['hello', 'class', 'how', 'are', 'you?']

for word in x:
    print(word)
    
for i, word in enumerate(x):
    print(i, word)
    
for i, word in enumerate(x):
    print(f"The {i+1}° word is {word}")

x = ['Pikachu', 'I', 'choose', 'you']
    
for i, word in enumerate(x):
    # CHALLENGE: insert some code here
    print(f"The {i+1}° word is {word}")

FIRST
The 1° word is Pikachu
The 2° word is I
The 3° word is choose
LAST
The 4° word is you

i = 0
while i < 10:
    print(f'run {i}')
    i = i + 1

# can also use a break statement
i = 0
while True:  # ALWAYS GOES UNTIL YOU BREAK
    print('run')
    i += 1  # same as i = i + 1   :D
    if i > 10:
        break

while True:
    new_emails = check_for_new_emails()
    
    important_people = ["mom", "dad", "Angela Dorothea Merkel"]
    
    for email in new_emails:
    	if email.sender in important_people:
        	call_me_on_my_cellphone()
            break
     
    # wait 5 seconds
    time.sleep(5)
    
    

x = 10
while x > 0:
	print("hello")
    x += 1
  

x = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

sliced = x[0]
print(sliced)
# 0

sliced = x[:3]
print(sliced)
# [0, 1, 2]

sliced = x[3:]
print(sliced)
# [3, 4, 5, 6, 7, 8, 9]

x = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

sliced = x[0:6:2]
print(sliced)
# [0, 2, 4]

# takes every number from 0 up to 6
# but not including 6
# with a step size of 2

sliced = x[:4]  # from the start to the 4th item
print(sliced)
# [0, 1, 2, 3]

sliced = x[4:]  # from the 4th item to the end
print(sliced)
# [4, 5, 6, 7, 8, 9]

sliced = x[::2]  # every second item
print(sliced)
# [0, 2, 4, 6, 8]

sliced = x[::-1]  # reverse the list
print(sliced)
# [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]

# works on strings!

s = 'hello world'

print(s[0:5])
# hello

print(s[6:])
# world

print(s[::2])
# hlowrd

print(s[::-1])
# dlrow olleh


# works on tuples too
(1,2,3,4,5)[2:]

x = set()  # start with empty set

# add some values
x.add(1)
x.add(2)
x.add(3)
x.add(4)
x.add(5)


print(x)

print(type(x))

x = set()  # start with empty set

# add some values
x.add(1)
x.add(2)
x.add(3)
x.add(4)
x.add(5)


print(x)

print(type(x))

x.remove(4)

print(x)
# {1, 2, 3, 5}

x.remove(4)

print(x)
# {1, 2, 3, 5}

x = {1, 2, 6, 7}

print(4 in x)
# False

print(2 in x)
# True

# set theory
x = {1, 2, 3, 4, 5}
y = {4, 5, 6, 7, 8}

print(x | y)  # union
print(x & y)  # intersection

sentences = [
    "hello world",
    "the quick brown fox jumps over the lazy dog",
]

x = {
    123456: "Susie",
    234567: "Jenny",
    345678: "Tim",
}

print(x.get(123456))
# Susie

# same as:
print(x[123456])

print(x[495])
# raises Error
# (key does not exist)

x = {"key": 42}

print(type(x))

print(x["key"])
# 42

# adding a new key-value pair
x["new_key"] = "hello"
x["fun"] = "python"

print(x)

# update a key
x["key"] = 66

print(x)
# {'key': 66, 'new_key': 'hello', 'fun': 'python'}

x = {
    123456: "Susie",
    234567: "Jenny",
    345678: "Tim",
}

print(123456 in x)
# True

x = {
    123456: "Susie",
    234567: "Jenny",
    345678: "Tim",
}

# can get the dictionary keys and values

print(x.keys())
# dict_keys([123456, 234567, 345678])

print(x.values())
# dict_values(['Susie', 'Jenny', 'Tim'])

keys = list(x.keys())
print(keys)
# [123456, 234567, 345678]

x = {
    123456: "Susie",
    234567: "Jenny",
    345678: "Tim",
}

# can get the dictionary keys and values

print(x.keys())
# dict_keys([123456, 234567, 345678])

print(x.values())
# dict_values(['Susie', 'Jenny', 'Tim'])

keys = list(x.keys())
print(keys)
# [123456, 234567, 345678]

# delete values

del x["key"]

print(x)

# looping over keys, values or items

for key in x.keys():
    print(key)

print("---")

for value in x.values():
    print(value)
    
print("---")

for key, value in x.items():
    print(key, value)

123456
234567
345678
---
Susie
Jenny
Tim
---
123456 Susie
234567 Jenny
345678 Tim

address_book = {
    "Susie": {
        "address": "123 Main St",
        "phone": "+49 123 456 7890",
    },
    "Jenny": {
        "address": "456 Maple Ave",
        "phone": "+41 123 333 3333",
    },
    "Tim": {
        "address": "789 Oak St",
        "phone": "+39 123 400 4040",
    },
}