Python Cheatsheet

Who is this for?

This crash-course makes the assumption that you already have some programming experience, but perhaps none with Python.

Comments

In [1]:
# You can write a comment using an octothorpe or 'hash' symbol

Printing to terminal

In [2]:
print("Hello World!")
Hello World!

Variables and assignment

In [3]:
my_number = 5
my_float = 0.2
my_string = "Hello"
also_my_string = 'Hello'
In [4]:
print("{} is of {}".format(my_number, type(my_number)))
print("{} is of {}".format(my_float, type(my_float)))
print("{} is of {}".format(my_string, type(my_string)))
print("{} is of {}".format(also_my_string, type(also_my_string)))
5 is of <class 'int'>
0.2 is of <class 'float'>
Hello is of <class 'str'>
Hello is of <class 'str'>

Terminal input

In [5]:
my_result = input('please enter a word: ')
print("result: {}".format(my_result))
please enter a word: Hello
result: Hello

Mathematical operations

In [6]:
my_result = 5 + 2 # add
print("result: {}".format(my_result))
result: 7
In [7]:
my_result = 5 - 2 # substract
print("result: {}".format(my_result))
result: 3
In [8]:
my_result = 5 * 2 # multiply
print("result: {}".format(my_result))
result: 10
In [9]:
my_result = 5 / 2 # divide
print("result: {}".format(my_result))
result: 2.5
In [10]:
my_result = 5 % 2 # modulo
print("result: {}".format(my_result))
result: 1
In [11]:
my_result = 5 ** 5 # exponent
print("result: {}".format(my_result))
result: 3125

Boolean operations

In [12]:
my_result = True
print("result: {}".format(my_result))

my_result = False
print("result: {}".format(my_result))
result: True
result: False
In [13]:
# and
my_result = False and False
print("result: {}".format(my_result))

my_result = False and True
print("result: {}".format(my_result))

my_result = True and False
print("result: {}".format(my_result))

my_result = True and True
print("result: {}".format(my_result))
result: False
result: False
result: False
result: True
In [14]:
# or
my_result = False or False
print("result: {}".format(my_result))

my_result = False or True
print("result: {}".format(my_result))

my_result = True or False
print("result: {}".format(my_result))

my_result = True or True
print("result: {}".format(my_result))
result: False
result: True
result: True
result: True
In [15]:
# not
my_result = not True
print("result: {}".format(my_result))

my_result = not False
print("result: {}".format(my_result))
result: False
result: True

Relational operations

In [16]:
my_result = 5 > 2 # greater than
print("result: {}".format(my_result))

my_result = 5 >= 2 # greater than or equal to
print("result: {}".format(my_result))

my_result = 5 < 2 # less than
print("result: {}".format(my_result))

my_result = 5 <= 2 # less than or equal to
print("result: {}".format(my_result))

my_result = 5 == 2 # equal to
print("result: {}".format(my_result))
result: True
result: True
result: False
result: False
result: False

Conditional statements

In [17]:
age = 17
uk_drinking_age = 18

if(age >= uk_drinking_age): # IF
    print("you can drinking!")
elif(age == 17):            # ELSE IF
    print("you can drink on your birthday!")
else:                       # ELSE
    print("you can't drink!")
you can drink on your birthday!

Data structures

In [18]:
# LIST
shopping_list = ["Carrots", "Onions", "Chicken", "Coconuts"]
print(shopping_list)
print(shopping_list [0]) # Python is zero-indexed

shopping_list.append("Ice cream")
print(shopping_list)
['Carrots', 'Onions', 'Chicken', 'Coconuts']
Carrots
['Carrots', 'Onions', 'Chicken', 'Coconuts', 'Ice cream']
In [19]:
# DICTIONARY
shopping_list = {"Carrots": 5, "Onions": 2, "Chicken": 1, "Coconuts": 1}
print(shopping_list)
print("Careful - dictionaries are not ordered in older versions of Python.")
print(shopping_list['Carrots'])
{'Carrots': 5, 'Onions': 2, 'Chicken': 1, 'Coconuts': 1}
Careful - dictionaries are not ordered in older versions of Python.
5
In [20]:
# TUPLE
my_result = (5, 6)
print(my_result)

my_result = (5, "hello", 5.5, True, 2)
print(my_result)
(5, 6)
(5, 'hello', 5.5, True, 2)

Loops

In [21]:
# FOR

shopping_list = ["Carrots", "Onions", "Chicken", "Coconuts"]

for item in shopping_list:
    print(item)
Carrots
Onions
Chicken
Coconuts
In [22]:
# FOR

for index in range(0,10):
    print(index)
0
1
2
3
4
5
6
7
8
9
In [23]:
# WHILE
number = 0

while(number < 18):
    print(number)
    number += 1
    
print("number was no longer below 18!")
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
number was no longer below 18!

Functions

In [24]:
def my_function(): # create a function
    print("No parameters passed in")
    
my_function()      # call a function
No parameters passed in
In [25]:
def another_function(name):
    print("Parameter passed in: {}".format(name))
    
another_function("Derek")
Parameter passed in: Derek
In [26]:
def greater_than(left_operand, right_operand): 
    my_result = left_operand > right_operand
    return my_result      # returning a value from the function

print(greater_than(5, 2)) # printing the value returned from the function
True

Packages

In [27]:
import datetime

print(datetime.datetime.now())
2019-07-12 19:37:47.117505