print("Hello World!")Hello World!Comments
Comments are lines of code that the programming language ignores. Comments are for the people writing and reading the code. In Python, you define a comment with a line starting with a #.
# This is a comment!
# Comments are for people to read
# Python does nothing with comments
print("This is not a comment!")This is not a comment!Python does Math
print(2+2)
print(3+1*4)
print((3+1)*4)4
7
16## + is for addition
## - is for subtraction
## * is for multiplication
## / is for division
## ** is for exponentprint(2.5+2.5) # this is going to do math
print("2.5+2.5") # This will print what is between the the quotes5.0
2.5+2.5Variables
A symbol/placeholder which represents a piece of data.
my_number = 2 #x now has the value of 2
print(x)
print("The value of my_number is", my_number)
my_name = "Butler" # x now has the value of "Butler"
print("The value of my_name has been changed to", my_name)Butler
The value of my_number is 2
The value of my_name has been changed to Butler# Variables should have good and descriptives names that too long
# Variable names can contain letters, numbers, or underscores (_)
# Variable names must start with a letterTypes
The type of a piece of data tells you what it is
Examples: * int: a whole number, no decimal (short for integer) * float: a number with a decimal * string: a sequence of characters between quotation marks (““)
x = 2 # this is a int
y = 2.0 # this is a float
print("The type of x is:", type(x))
print("The type of y is:", type(y))The type of x is: <class 'int'>
The type of y is: <class 'float'>Performing Math with Variables
x = 2
y = 3
add = x+y
sub = x-y
mul = x*y
div = x/y
exp = x**y
print("Addition:", add)
print("Subtraction:", sub)
print("Multiplication:", mul)
print("Division:", div)
print("Exponent:", exp)Addition: 5
Subtraction: -1
Multiplication: 6
Division: 0.6666666666666666
Exponent: 8temp_C = -30 # This is a temperature in Celsius
temp_F = 1.8*(temp_C) + 32 # This is the temperature converted to Farenheit
temp_K = temp_C + 273.15 # This is a temperature in Kelvin
print("The temperature in Celsius:", temp_C)
print("The temperature in Farenheit:", temp_F)
print("The temperature in Kelvin:", temp_K)The temperature in Celsius: -30
The temperature in Farenheit: -22.0
The temperature in Kelvin: 243.14999999999998# Code cells remember what was above
print("The temperature in Celsius:", temp_C)The temperature in Celsius: -30Conditional Statement
Conditional statements perform differently depending on if a given condition is true or false.
temp_C = 20 # Redefining
if temp_C > 20:
print("It is hot!")
print("We should go to the pool!")temp_C = 19 # Redefining
if temp_C < 20:
print("It is cold!")
print("Bring a jacket!")
else:
print("It is hot!")
print("Do not bring a jacket!")It is cold!
Bring a jacket!temp_C = 23 # Redefining
if temp_C < 15:
print("It is cold!")
elif temp_C <= 22:
print("It is moderate!")
elif temp_C <= 30:
print("Its kinda hot!")
else:
print("It is hot!")Its kinda hot!Boolean
A new data type that must evaluate to either True or False
print(type(False))<class 'bool'># > is greater than
# < is less than
# >= is greater than or equal to
# <= is less than or equal to
# == is equal to
# != is not equal toprint(3!=2)TrueFunctions
Functions prevent to need to copy and paste code by letting you reuse code by referencing a name. They work variables but for large pieces of code.
def about_me():
print("My name is Julie Butler")
print("I have a dog")
print("I live in Alliance")
print("I am a professor")# Once you have defined a function, it can be referenced
# anywhere in the notebook
about_me()My name is Julie Butler
I have a dog
I live in Alliance
I am a professor# Functions can be passed information (called arguments)
# Functions can return information
# Docstrings are a special type of comment for a function
def C_to_F(temp_C):
"""
Converts a temperature in Celsius to Farenheit.
Arguments:
temp_C (float or int): a temperature in Celsius
Returns:
temp_F (float or int): a temperature in Farenheit
"""
temp_F = 1.8*temp_C+32
return temp_Fprint(C_to_F(-50))
print(C_to_F(20))-58.0
68.0# Values returned by functions can be saved in variables
temp_F_32 = C_to_F(32)
print("32 Celsius in Farenheit is", temp_F_32)32 Celsius in Farenheit is 89.6# Functions can have more than one argument
# and more than one return type
def convert_temp (temp_C, isPrint):
"""
Convert a temperature in degrees Celsius to both
Farenheit and Kelvin and will print the conversion
if needed.
Arguments:
temp_C (float or int): a temperature in Celsius
isPrint (boolean): if True, print information about the temperatures
Returns:
temp_F (float): the temperature in Farenheit
temp_K (float): the temperature in Kelvin
"""
# Calculate the temperature in Farenheit and Kelvin
temp_F = 1.8*temp_C+32
temp_K = temp_C + 273.15
# Print information if needed (if isPrint is True)
if isPrint:
print("The temperature in Celsius is", temp_C)
print("but in Farenheit it is", temp_F)
print("and in Kelvin it is", temp_K)
# Return the calculated temperatures
return temp_F, temp_Ktemp_F_15, temp_K_15 = convert_temp(15, False)print(temp_F_15, temp_K_15)59.0 288.15Lists
List is a data type which let’s you store, access, and manipulate large amounts of information
# Lists are defined with square brackets []
# Each piece of data in a list is called an element
my_list = [10, 22, "Julie", 5, 28]
print(type(my_list))<class 'list'># Each element has a location associated with it identified by a number called an index
# The index of element can be used to extract it from the list
# The index of the first element is 0, the index of the last element is length of list - 1
print(my_list[4])28# Save one element of the list with a variable
element = my_list[3]
print(element)5# Find the length of a list using the len function
print(len(my_list))5# Access multiple elements with index splicing
# The first index is inclusive (meaning we use it)
# The second index is exclusive (meaning we up to it, but do not include it)
# The result of using an index splice on a list is a list
print(my_list[0:3])[10, 22, 'Julie']my_smaller_list = my_list[1:4]
print(type(my_smaller_list))<class 'list'># Lists have functions that give them extra abilities
# len is one of the functions that gives us the length of the list
# append is a function that let's us add data to a list
print(my_list)
my_list.append("sponge") # append adds to the end of the list
print(my_list)[10, 22, 'Julie', 5, 28]
[10, 22, 'Julie', 5, 28, 'sponge']# pop lets you remove an element at a given index
print(my_list)
my_list.pop(1)
print(my_list)[10, 22, 'Julie', 5, 28, 'sponge']
[10, 'Julie', 5, 28, 'sponge']# sort and reverse let you control the order of elements in the list
new_list = [15, 19, 17, 16, 18]
print(new_list)
# orders the list in ascending order (smallest to largest)
new_list.sort()
print(new_list)
# flips the order of the list (first element becomes last element, last element becomes first element)
new_list.reverse()
print(new_list)[15, 19, 17, 16, 18]
[15, 16, 17, 18, 19]
[19, 18, 17, 16, 15]# min and max let you pull out the smallest and largest values in a list
print(min(new_list))
print(max(new_list))15
19# Reverse list indexing let's you access elements starting from the end of the list
print("The last element in the list is", new_list[4])
print("The last element in the list is", new_list[-1])
print("The second to last element in the list is", new_list[-2])The last element in the list is 15
The last element in the list is 15
The second to last element in the list is 16Strings
# A string is a bunch of characters between double quotes
my_name = "Julie Butler"
print(my_name)Julie Butler# You can access the letters of a string with indices or index splicing
print(my_name[1])uprint(my_name[4:8])e Buprint(my_name.upper())JULIE BUTLERprint(my_name.lower())julie butlerprint(my_name.count("l"))2