Lecture of 20th October at 13:15

(* Create a simple function to add 1 to a value *)
>>> def mfif(n):
...    return n+1

(* What values will these return? *)
>>> mfif(2)
>>> mfif(2.0)
>>> mfif("a")

(* How to create an anonymous function *)
>>> msif = lambda n:n+1

(* What will these return? *)
>>> msif(2)
>>> type(lambda n:n+1)
>>> msif(2+5j)
>>> msif(2.0+5.0j)

(* Seeing where the function has been stored. Does the location change? *)
>>> (lambda x:x)
>>> (lambda x:x)

(* What happens when we compare an anonymous function to itself? *)
>>> (lambda x:x) == (lambda x:x)
>>> (lambda x:x) is (lambda x:x)
>>> x = y = (lambda x:x)
>>> x == y
>>> x = (lambda x:x) ; y = (lambda x:x)
>>> x == y

(* What does this print out? Why is the result interesting? *)
>>> [lambda x:x]*(10**3)

(* Lists in python are mutable. What will this output? *)
>>> l = [lambda x:x]*4+[lambda x:x]*4
>>> l[0] = 4
>>> l

(* We can print a sorted version of a list without changing the original list *)
>>> l = list(range(4,-1,-1))
>>> sorted(l)
>>> l

(* Sorting works lexicographically on character lists. What will this return? *)
>>> sorted(["a","A","bb"])

(* Single and double quotes are synonymous in Python *)
>>> ("a",'a')

(* But single and double quotes have different lexicographical values. What will this return? *)
>>> '"a"' == "'a'"

(* Creating a list which holds every value from 0 to 99 *) 
>>> [ x*x for x in range(100) ]

(* This notation can be used with two "for" loops. This returns a chess board *)
>>> [ (x,y) for x in range(8) for y in range(8) ]

(* This function will return true if the number is odd, and false if the number is even. Uses binary comparison *)
>>> 5&1
>>> not(5&1)
>>> not(4&1)

(* How to delete items from a list *)
>>> x = [1,2,3,4,5]
>>> del x[0]
>>> x
>>> del x[-1]
>>> x

(* Python lists have a sort-in-place method. What will these return? *)
>>> x = [5,4,3,2,1]
>>> x.sort()
>>> x
>>> x = [4,5,1,3,2]
>>> x.sort()
>>> x
>>> x = [[5,3],[3,4],[1,2]]
>>> x.sort()
>>> x