Generate Random Numbers and Multiplication Tables in Python

1. Largest of x random numbers • Write a function that takes 2 integers (x and y) as input parameters , and generates x random numbers between 0 and y. It finds the largest of those random numbers. deffind_largest(x,y): largest = 0; count = 0; while count < x: rnum = randrange(0,y) if rnum > largest: largest = rnum count +=1 return(largest); print(find_largest(7,50))

2. Try: Multiplication tables • def func(x): • count = 0 • while (count <= 10): • print(count*x) • count += 1 • return (total) • print(func(5)) • def fancyfunc(x): • count = 0 • while (count <= 10): • print(str(count)+"x"+str(x)+"="+str(count*x)) • count += 1 • return (total) • print(fancyfunc(7)) • Write a function that takes as an input parameter a number, and then prints out that number's multiplication table up through 10, • e.g., if the number was 4, you'd get 0 4 8 12 … 40 (Or Fancier version): 0x4=0 1x4=4 2x4=8 3x4=12 … 10x4=40

3. Average: count • Write a function that takes no inputs. It generates 1000 random numbers between -100 and 100. It counts how many of the random numbers are below 0 and how many are at or above 0. It then tells you which is more likely, below 0 or at or above 0. • Starting condition? • What makes the loop stop? • What inside the loop changes so that the loop will stop? from random import * def beloworabove(): count = 0 below = 0 above = 0 while (count < 1000): rand = randrange(-100,100) if (rand < 0): below += 1 else: above += 1 count += 1 if below > above: return("generated " + str(below) + " numbers below 0") else: return ("generated " + str(below) + " numbers above 0") print(beloworabove())

4. What do we get? from math import * def f(a,b): n = min(a,b) i = 1 g = 1 while (i <= n): if (a%i == 0) and (b%i == 0): g = i i = i+1 return(g) print(f(32,24)) print(f(13,8)) print(f(24,16))

5. For loop: another type of loop • We use For loops when we know exactly how many times the loop will occur • Form: for variablein [value1, value2,value3…lastvalue]: calculations • Example: def f(): for x in [1,2,3,4,5]: print(x) return(x) print(f())

6. More for loops: def f(): for x in [1,3,5,7,9]: print(x) return(x) print(f()) def f(): for x in [2,7,1,9,4]: print(x) return(x) print(f())

7. More for loops: def f(): y = 0 ct = 0 for x in [3.2, 7.1, 8.0, 3.4, 5.1]: print("including " + str(x)) ct +=1 y = y + x return(y/ct) print(f())

8. Loops with strings: def f(y): ct = 0 for x in ["puppy","bunny","puppy","bird","echidna","puppy"]: if x == y: ct += 1 return(ct) print(f("puppy"))

9. More for loops: def f(): for x in [0,1,2,3,4]: print(x) return(x) print(f()) • Shortcut: using range def f(): for x in range(5): # range(5) = [0,1,2,3,4] print(x) return(x) print(f())

10. Same? def whilefunc(y): count = 0 total = 0 while (count < y): total += count count += 1 return (total) print(whilefunc(5)) def forfunc(y): total = 0 for x in range(y): total += x return(total) print(forfunc(5))

11. More on Range: def f(): for x in range(-3,3): # from -3 up to but not including 3, e.g., [-3,-2,-1,0,1,2] print(x) return(x) print(f()) def f(): for x in range(-3,3,2): # from -3 up to but not including 3, by increments of 2, e.g., [-3,-1,1] print(x) return(x) print(f()) (Can we make a loop go backwards?)

12. What does this do? def f(): y = 1000 total = 0 for x in ["2","7","1","9"]: total = total + int(x) * int(y) y /=10 return(total) print(f())

13. How about this? def f(z): y = int(input("enter a number: ")) for x in range(1,y): for q in range(1,z): print (str(q)+ "*"+str(x)+"=\t"+str(x*q)) print ("\n") return f(4)

14. Just about anything you can do with lists: Len, in def f(x): if "e" in x: return("e is in your message.") else: return("e is not in your message.") strvar = “puppies are cute” print(f(strvar)) z = len("cat")

15. Positions def f(wv): return(wv[3]) wordvar = “cats” print(f(wordvar))

16. Slicing (Different from Indexing) Copying parts of strings: 0 1 2 3 4 5 | p | i | z | z | a | -5 -4 -3 -2 -1 def f():word = “pizza” return(word[0:5]) def g(): word = “pizza” return(word[1:3]) def h(): word = “pizza” return(word[-4:-2]) def i(): word = “pizza” return(word[-4:3])

17. Shortcuts 0 1 2 3 4 5 | p | i | z | z | a | -5 -4 -3 -2 -1 word=“pizza” word[0:4] pizz word[:4] pizz word[2:5] zza word[2:] zza

18. # display a slice def g(s,f,wd): return("wd["+str(s)+":"+str(f)+"] is "+str(wd[s:f])) print(g(3,7,"sesquipedalian"))

19. Strings are Immutableword of the day • Can: • x = "catamaran" • print(x.count("a")) • print(x.index('a')) • Can’t (if it changes the string, we can’t do it) • Append (use + instead) • Reverse() • Pop() • Insert() • Sort()

20. What does this do? def f(): strvar = input("enter a string: ") var1 = "" for x in range(len(strvar) - 1,-1,-1): var1 += strvar[x]; return(var1) print(f())

21. This one? def f(): strvar = input("enter a number: ") y = 1 z = 0 var1 = "" for x in range(len(strvar) - 1,-1,-1): z += int(strvar[x]) * y; y*=10 return(z) print(f())

22. What does this give you? def f(lv): x = len(lv) print(x) for y in range(0,x): if "t" in lv[y]: print(lv[y]) return listvar = ["ham","am","boat","goat","there","anywhere"] f(listvar)

23. What does this do? deff(word): high = len(word) low = 0 newstr= "" for i in range(10): position = randrange(low, high) newstr+= word[position] return(newstr) wvar = "sesquipedalian" print(f(wvar))

24. How about this one? deff(m): new_m= "" SPECIAL = "dlmstp" for k in m: if k.lower() not in SPECIAL: new_m+= k return(new_m) mvar = "Hi, my name is Lassie" print("Your message is: now" + f(mvar))

25. Something you can’t do word = “ night”; word[0] = “s”; Instead: newword = “” for x in “night”: if x == “n": newword+= “s" else: newword+= x

26. What do you get? deff(message): newmessage= "" for x in message: if x == "g": newmessage+= "l" else: newmessage+= x return(newmessage) mvar= "pogysyggabicaggy" print("new string: " + f(mvar))