2. Largest of x random numbers def find_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)) 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.

3. What do we get? def q(x,y): ct = 0 while (ct < x): ct2 = 0 while (ct2 < y): print(ct + ct2) ct2 += 1 ct += 1 return q(4,3) Rules:  The contents of the while loop is only what is indented under the while loop  We do the contents of the while loop over and over until the while loop’s condition becomes false.  Only then do we do what is below the while loop.

4. What does this print out? def h(x): ct = 1 while (ct <= x): ct2 = ct while (ct2<=x): print(ct2, end=“\t") #prints a tab after every ct2 ct2 += 1 ct += 1 print("\n") #this is a line break (starts a new line) return h(5)

5. Can you reverse it Output: 1 2 3 4 5 2 3 4 5 3 4 5 4 5 5 def h(x): ct = 1 while (ct <= x): ct2 = ct while (ct2<=x): print(ct2, end=" ") ct2 += 1 ct += 1 print("\n") return h(5) def h(x): ct = 1 while (ct <= x): ct2 = 1 while (ct2<=ct): print(ct2, end=" ") ct2 += 1 ct += 1 print("\n") h(5) Output: 1 1 2 1 2 3 1 2 3 4 1 2 3 4 5

6. What do we get? def g(a,b): while (a != b): while (a > b): a = a-b while(b>a): b = b-a return(a) print(g(6,20))

7. def f14(x): k = 0 n = -1 v = x while k <= (x*2): m = 0 while (m < v): print(v, end = "") m += 1 if (v == 0): n = 1 else: print() v += n k+=1 print() f14(3)

8. Lists: a new type!  We've got:  ints  floats  booleans  strings  and now… (drum roll)  LISTS!  sets of a thing (e.g., sets of ints)

9. Creating Lists  To create a list, put a number of expressions in square brackets: listvar = [ ] #Empty list with nothing in it.  A list with things in it: # create a list with some items listvar1 = [2,10,8,4,17] listvar2 = [“spider leg”,”toe of frog”,”eye of newt”, “bat wing”, “slug butter”, ”snake dandruff”] First list is a list of ints Second list is a list of strings.

10. Lists  Overview  The list type is a container that holds a number of objects, in a given order.  Lists have an order to them  Like a string, in which the order of the characters matters  Examples of lists:  Sound files: a long list of numbers measuring vibrations in the air  any vibrational measurements  The order of the measurements of vibration is dependent on when they occurred in time.  List of class participants  Measurements of movements (e.g., weather)

11. Lists: listvar2 = [“spider leg”,”toe of frog”,”eye of newt”, “bat wing”, “slug butter”,”snake dandruff”] Index 0 1 2 3 4 5 listvar1 = [2, 10, 8, 4, 17] Index 0 1 2 3 4 So to use a particular item in the list: x=listvar2[3] #”bat wing” y=listvar1[1] #10 z=listvar2[0] #”spider leg”

12. Lists: Like strings, we can use: len in listvar2 = [“spider leg”,”toe of frog”,”eye of newt”, “bat wing”, “slug butter”,”snake dandruff”] listvar1 = [2, 10, 8, 4, 17] get the length of a list len(listvar2) # will give you 6 if “eye of newt" in listvar2: return(“we can do chemistry!") else: return(“Sorry, no chemistry today.”)

13. Lists: Index: 0 1 2 3 4 5 listvar2 = [“spider leg”,”toe of frog”,”eye of newt”, “bat wing”, “slug butter”,”snake dandruff”] Slice: 0 1 2 3 4 5 6 -6 -5 -4 -3 -2 -1 listvar1 = [2, 10, 8, 4, 17] Slicing: x = listvar2[3:5] #x now holds [“bat wing”,”slug butter”] y = listvar1[1:2] #y now holds [10]

14. Lists:Slicing (Different from Indexing) Index: 0 1 2 3 4 5 listvar2 = [“spider leg”,”toe of frog”,”eye of newt”, “bat wing”, “slug butter”,”snake dandruff”] Slice: 0 1 2 3 4 5 6 -6 -5 -4 -3 -2 -1 def f(): return(listvar[0:6]) >>[“spider leg”,”toe of frog”,”eye of newt”, “bat wing”, “slug butter”,”snake dandruff”] def g(): return(listvar2[1:3]) >>[”toe of frog”,”eye of newt”] def h(): return(listvar2[-4:-2]) >>[”eye of newt”,”bat wing”] def i(): return(listvar2[-4:4]) >>[”eye of newt”,”bat wing”]

15. Shortcuts Index: 0 1 2 3 4 5 listvar2 = [“spider leg”,”toe of frog”,”eye of newt”, “bat wing”, “slug butter”,”snake dandruff”] Slice: 0 1 2 3 4 5 6 -6 -5 -4 -3 -2 -1 listvar2[0:4] [“spider leg”,”toe of frog”,”eye of newt”,”bat wing”] listvar2[:4] [“spider leg”,”toe of frog”,”eye of newt”,”bat wing”] listvar2[3:6] [“bat wing”, “slug butter”,”snake dandruff”] listvar2[3:] [“bat wing”, “slug butter”,”snake dandruff”] listvar2[:] [“spider leg”,”toe of frog”,”eye of newt”, “bat wing”, “slug butter”,”snake dandruff”]

16. Stuff we can do to lists that we can’t do with strings:) listofstuff = [“ant", “bear", “cat", “dog“,”elephant”,”fox”] # assign by index listofstuff[0] = “aardvark" print(listofstuff) >>>[“aardvark", “bear", “cat", “dog“,”elephant”,”fox”] # assign by slice listofstuff[3:5] = [“dolphin"] print(listofstuff) >>>[“aardvark", “bear", “cat", “dolphin”,”fox”] # delete an element del listofstuff[2] print(listofstuff) >>>[“aardvark", “bear", “dolphin”,”fox”] # delete a slice del listofstuff[:2] print(listofstuff) >>>[ “dolphin”,”fox”]

17. Concatenate(join) lists list1 = [“skeletons", “zombies ", “witches"] list2 = [“vampires", “ghouls ", “werewolves"] list3 = list1 + list2 print(list3) >>>[“skeletons", “zombies ", “witches“,”vampires", “ghouls ", “werewolves"] list1 +=list2 print(list1) >>>[“skeletons", “zombies ", “witches“,”vampires", “ghouls ", “werewolves"] list1[3]? list1[0]? list1[6]?

18. Note: adding to the end of the list: list1 = [“skeletons", “zombies ", “witches“,”vampires", “ghouls ", “werewolves"] We CAN do: list1[4] = “ghosts” print(list1) >>> [“skeletons", “zombies ", “witches“,”vampires", “ghosts ", “werewolves"] We CAN’T do: list1[6] = “poltergeists” (why not?)

19. Appending to end of list: list1 = [“skeletons", “zombies ", “witches“,”vampires", “ghouls ", “werewolves"] We CAN’T do: list1[6] = “poltergeists” Instead: list1.append(“poltergeists”) print(list1) >>[“skeletons", “zombies ", “witches“,”vampires", “ghouls ", “werewolves“, ”poltergeists”] Append adds an element to the end of a list (sets aside more RAM memory) Always to the end! It is a method (function) that belongs to anything that is of the list type Appending doesn’t work with strings (They’re immutable!)

20. List Methods  Methods are functions that manipulate lists specifically  lists are objects (object-oriented programming)  Objects have methods (functions) associated with them.  E.g., dog objects might have a walking function  Square objects might have a calc_area function  List objects have functions: e.g.,  Add an element  reverse the list  Sort a list  Etc.

21. Removing an item from the list: list1=[“skeletons", “zombies ", “witches“,”vampires", “ghouls ", “werewolves“, ”poltergeists”] list1.remove(“werewolves”) >>[“skeletons", “zombies ", “witches“,”vampires", “ghouls ",”poltergeists”] Trying to remove something that isn’t in the list gives you an error: list1.remove(“ghosts”) #ERROR So check: if “vampires” in list1: list1.remove (“vampires”) print (list1) >>>[“skeletons", “zombies ", “witches“, “ghouls ", ”poltergeists”] remove() ONLY removes the first occurrence of an item in the list: list2 = [8,2,3,1,5,3,8,4,2,3,5] list2.remove(2) print(list2) >>[8,3,1,5,3,8,4,2,3,5]

22. list1=[“skeletons", “zombies ", “witches“, “ghouls ", ”poltergeists”] Reversing the order of the list: list1.reverse() >>>[‘poltergeist’,’ghouls’,’witches’,’zombies’,’skele tons’] Sorting the list list1.sort() >>>[‘ghouls’,’poltergeists’,’skeletons’,’witches’,’zo mbies’] Sorting the list list1.sort(reverse = True) >>>[‘zombies’,’witches’,’skeletons’,’poltergeists’,’g houls’]

23. Other methods available for lists  count(value) – counts the number of times value occurs in list  list2 = [8,2,3,1,5,3,8,4,2,3,5,3] x = list2.count(3) print(x) >>>4  index(value) – returns index of first occurrence of value list1=[“skeletons", “zombies ", “witches“, “ghouls ", ”poltergeists”] y = list1.index(“witches”) print(y) >>>2

24.  pop([f]) – returns value at position f and removes value from list. Without f, it pops the last element off the list list1=[“skeletons", “zombies ", “witches“, “ghouls ", ”poltergeists”] x=list1.pop() print(x) >>”poltergeists” print (list1) >> =[“skeletons", “zombies ", “witches“, “ghouls ”] x=list1.pop(2) print(x) >>”witches” print (list1) >> [“skeletons", “zombies ", “ghouls ”]  insert(f,value)- inserts value at position f list1.insert(1,’dragons”) print(list1) >>>[“skeletons", “dragons”, “zombies ", “ghouls ”]

25. def rg(x,y): while len(x) > 0: y.append(x.pop()) return(y) print(rg(['witch','ghost','werewolf','vampire'],[]))

26. def rf(y,ls): while ls.count(y)>0: if y in ls: z = ls.index(y) ls.pop(z) return(ls) x = ['a','c','b','a','d','b','a','c','b','f','c','b'] print(rf('c',x))

27. def k(x,y): k = True while y < len(x)//2: if (x[y] != x[len(x) - y-1]): k=False y+=1 return (x[y] == x[len(x) - y-1]) and k print(k("rotator",0)) print(k("clue",0))

28. def lr2(x,y,ls): while x < len(ls): if (ls[x] > y): y=ls[x] x += 1 return(y) listarr = [3,2,7,3,1] print(lr2(0,0,listarr))

29. def g(x,y): while (len(x) > 1): i = randrange(len(x)) y+=x[i] x = x[:i]+x[i+1:] return(y+x) print(g("computer","")) #A game comes to mind…

30. def f(x,y,z): while x < len(z): if y> z[x]: y=z[x] x+=1 return(y) print(f(0,"zzyrgy",['ghoul','zombie','werewolf','vampire','ghost','pumpkin'])) def g(x,z): while x < len(z): q = f(0,"zzyrgy",z[x:]) i = z.index(q) t = z[x] z[x] = z[i] z[i] = t x+=1 return(z) print(g(0,['ghoul','zombie','werewolf','vampire','ghost','pumpkin']))

31. def h(x): y = "" k = 0 while k<len(x): y+=(x[k][k]) k+= 1 return(y) ls = ['coffin','creepy','hayride','corpse','ghastly'] print(h(ls))