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Cheatography

Python cheat sheet Cheat Sheet by

Commands/ Functions

print()
displays inform­ation of the screen
input()
receives info from the the user
float()
converts a value to decimal
int()
integer; coverts a value to an integer
str()
string; coverts a value to a string
#
Comment; no effect

Vocabulary

variable
something that can change
string
a list of characters
Integer number
Whole number/ counting number
Float number
The number in decimal
Syntax
Grammar/ Structure of language
Modulo
Find the remainder
Boolean
True/False

Example

Print (2) – integer
Print (2.5) – float
Print (“Hello”) – string
Print (mystr) – variable
Print (str,”­Hi”­,2,1.0) – commas

mystr = “Hi”
mystr – name
“Hi” – value can change

print (int(1.5)) – 1
print (int(“2”)) – 2
print(­flo­at(1)) - 1.0 anything to a float

Math

==
equal to
!=
no equal to
<
less than
>
more than
<=
less than or equal to
>=
more than or equal to
%
Modulo, Find the remainder

Addition

string + string
combines the strings together
string + number
crash
number + number
math (addition)

Multip­lic­ation and Exponents

string­*string
CRASH!
string­*number
combines the string multiple times
number­*number
Multiply (Math)
string ** number
CRASH!
string ** string
CRASH!
number ** number
Exponent (Math)

Naming Convention

Rule for giving name
- letter
- numbers
- unders­core_

Valid name
- _myStr
- my3
- Hello_name

Invalid name
- 3my="hi­" -- cannot start with number
- first name="h­i"
- first-name

Reverse word

word = input("please enter a word.")

"""
letter_num = 0
reverse = ' '
while letter_num < len(word) :
    reverse = word[letter_num] + reverse
    letter_num = letter_num + 1
"""
reverse = ' '
for letter in word:
    reverse = letter + reverse
print ("Reverse: ",reverse)

Countdown Machine

while True:
    user_number = input("Please enter a number")
    number = int(user_number)
    countdown_string = ""
    while number > 0:
        countdown_string = countdown_string + str(number)
        number = number - 1
    print (countdown_string)

List

shoppinglist = ['coke zero', 'bacon', 'water', 'jelly', 'gummy bears']

print (shoppinglist)

print (shoppinglist[0])

list_num =0
while list_num < len(shoppinglist):
    print ("List:", shoppinglist[list_num])
    list_num = list_num + 1

for item in shoppinglist:
    print (item)

numbers = range (1,6)
for num in numbers:
    print (num)

# a string is a list of characters, letters, numbers etc.

mystr = "hello"
for letter in mystr:
    print (letter)

shoppinglist = ['coke zero', 'bacon', 'water', 'jelly', 'gummy bears']
num = 0
for w in shoppinglist:
    num = num + 1
    print (num)

shoppinglist = ['coke zero', 'bacon', 'water', 'jelly', 'gummy bears']
num = 0
for w in shoppinglist:
    num = num + 1
print (num)
 

Finding area of a circle

while True:
    user_radius = input("Please enter the radius of the circle:")
    radius = float(user_radius)
    pi = 3.1415

    area = (piradius*2)

    print ("The area of the circle is", area)

Calculator program

def calc (num1, num2, operation):
    if operation == "sum":
        return sum (num1,num2)
    elif operation == "product":
        return product (num1,num2)
    elif operation == "diff":
        return diff (num1,num2)
    elif operation == "div":
        return div (num1,num2)
    # use if/elif/else to check what operation to do
    # call the correct function and return the answer
def sum (a, b):
     return a+b
    # calculate the sum of a and b
    # return the answer
def product (a, b):
    return a*b
    # calcualate the product of a and b
    # return the answer
def diff (a, b):
    return a-b
    # calculate the difference between a and b
    # return the answer
def div (a, b):
    if b!=0:
        return a/b
    else:
        return ("Error")
    # calculate the division of a and b
    # return the answer

print (calc (10, 0, "div"))
print (calc (1, 2,"sum")) # output should be 3
print (calc (4, 2, "diff")) # output should be 2
print (calc (9, 3, "div" )) # output should be 3
print (calc (2 ,12, "product" )) # output should be 24

Finding the area of the triangle and its prism

#write a function

#name: areaofTriangle
#parameters: base height
#return: area

user_base = float(input ('Enter the base of the triangle: '))
user_height = float(input('Enter the height of the triangle:'))

def areaOfTriangle (base, height):
    return 0.5baseheight #or 1/2

#functioncall

print ('The area of the triangle is', areaOfTriangle(user_base, user_height))

#write function compute volume of prism

#name: volumeOfPrism
#parameters: base, height, prism_height
#return volume

def volumeOfPrism (base,height,prism_height):
    # area * prism_height
    volume = areaOfTriangle (base,height) * prism_height
    return areaOfTriangle (base,height) * prism_height

user_prism_height = float(input('Enter the height of the prism:'))
print ('The area of the prism is', volumeOfPrism (user_base,user_height,user_prism_height))

Maximum

# write a function that returns the largest of two values
# name: max2
# arguments: num1, num2
# return: the largest value
def max2 (num1,num2):
    maxvalue = num1
    
    if num2 > maxvalue:
        maxvalue = num2
    return maxvalue

print (max2(3,4))

# write a function that returns the largest of three values
# name: max3
# arguments: num1, num2, num3
# return: the largest value

def max3 (num1,num2,num3):
    maxvalue = num1
    
    if num2 > maxvalue:
        maxvalue = num2
   
    if num3 > maxvalue:
        maxvalue = num3
        
    return maxvalue

print (max3(3,4,8))

# write a function that returns the largest number in a list
# name: maxlist
# argument: list
# returns the largest value in the list


def maxlist (list):
    maxvalue = list[0]
    for item in list:
        if item > maxvalue:
            maxvalue = item
            
    return maxvalue

list = [1,2,3,6,19,50,2,4,5]
print (maxlist(list))

1. Multip­lying number

#Receive input from the user as a float, and print out half of that number. e.g. user enters 12.5, print out 6.25

user_input = input("Please enter a number:")
number = float(user_input)
finalnumber = 0.5*number
print(finalnumber)

2. Output

#What is the output of the following code:
y = True
print (not y or 2<3)
#output is True

3. Error

message = "hello"
if (len(message) >5)
print ("Message too long")
else:
     print ("Message is good")

line 3 has an error because it has no indent

4. Divisible by 3

#create a program to receive a number from the user and determine if that number
#is divisible by 3
user_input = input("Please enter a number:")
number = int(user_input)
if number %3 == 0:
    print(number,"is divisible by 3")
else:
    print (number, "is not divisible by 3")
 

5. Even Number

# print all the even numbers from 1 to 100 using a while loop
num = 2
while num <= 100:
    print (num)
    num = num+2

6. Output 2

#What is the output of the following code?

condition = True
number = 5

if condition == False: #False
    number = number ** 2
elif number <5: #False
    number = number * 2
elif condition == True: #True
    number = number%2 #5%2=1
else:
    number = number/2
print (number) # output = 1

7. my list (method 1)

#Given a list called mylist, print all elements from the list using a loop
mylist = ["Milly","Prim","Pizza"]
for item in mylist:
    print (item)

7. List: while loop (method 2)

#while loop solution
mylist = [1,2,3,4,5]
num = 0
while num < len(mylist):
    print (mylist[num])
    num = num+1

9. Multip­lic­ation Table

#Write a function called multiplicationTable that asks the user for a number and
#computes its multiplication table.

def multiplicationTable ():
    user_input = input ("Enter a number:")
    num = int(user_input)
    count=1

    while count <= 10:
        print (num,"",count,"=",numcount)
        count = count+1

#function call
multiplicationTable()

1) Multiply 5

#Write a program that receives input from the user, converts it to an integer,
#and print the product of the integer and 5

user_input = input("Please enter a number.")
user_input = int(user_input)
product = user_input * 5
print (product)

2) Output

#What is the output of the following code?
x = False
print (x and True or 1 == 1)
#False and True = False
# False or True = True

# output is True

3) Error 2

#condisder the following code

def doubleValue(value):
return value*2
print (doubleValue(4))

#line 2 has error because it is not indented

4) Types of number

#write a program that receives a number from the user and determines if that
#number is negative,zero or positive.

user_input = int(input("Please enter a number:"))
if user_input > 0:
    print (user_input,"is positive")
elif user_input == 0:
    print (user_input,"is zero")
else:
    print (user_input,"is negative")

5) Even numbers while loop

# write a program that prints all the even numbers from -100 to -1 using a
#while loop

num = -100
while num <= -2:
    print (num)
    num = num + 2

6) Output 2

#What is the output of the following code:

condition = 2<3 #True
number = 3

if condition != True: #True != True ;False
    number = number ** 2
elif number <= 0: #3 <= 0 ;False
    number = number * 3
elif number > 3: # 3>3 ; False
    number = number%10
else: #everything is False do must do else
    number = number - 1 * 2 # number - 2; 3-2=1; 1

print (number) # 1

8) 0......

#complete the program below by filling in the blank
# Expected output of program
# 0
# 01
# 012
# 0123
# 01234

mystring = ""
count = 0
while count <= 4:
    mystring = mystring +str(count)
    print (mystring)
    count = count + 1

9) Area of Ellipse

# Write a function called areaOfEllipse () that computes the area of an ellipse
#using the equation pir1r2
# The function should be given 2 parameters (radius1 and radius 2) and should
#return the area

def areaOfEllipse (radius1,radius2):
    pi = 3.1415
    area = piradius1radius2
    return area
#function call
area1 = areaOfEllipse(2,3)
print(area1)

11) Even and Odd

# Write a program that repeatly receives positive integers from the user. When
# the user enters a negative integer, exit the loop and print how many of the
# numbers entered were even and odd.

evencount = 0
oddcount = 0

while True:
    user_input = int(input("Enter a number:"))
    if user_input < 0:
        print ("Evencount=", evencount)
        print ("Oddcount=",oddcount)
        break
    elif user_input > 0:
        if user_input % 2 == 0:
            evencount = evencount + 1
    else:
        oddcount = oddcount + 1

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