Cheatography

Python cheat sheet Cheat Sheet by Milly

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

 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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