- Creating Lists
print('Empty lists:')
a1 = [ ]
a2 = list()
print(' ', a1, a2)
print('Non-empty lists:')
a3 = [2, 3, 5, 7]
a4 = ['mixed types', True, 42]
print(' ', a3, a4)
print('Variable-length lists:')
a5 = [42] * 10
print(' ', a5)
print('Converting non-lists to lists:')
a6 = list(range(5))
a7 = list('yes!')
print(' ', a6, a7)
- List Functions
a = [ 2, 3, 5, 2 ]
print('a = ', a)
print('len =', len(a))
print('min =', min(a))
print('max =', max(a))
print('sum =', sum(a))
- Accessing Elements
a = [2, 3, 5, 7, 11, 13]
print('Indexing works just like strings:')
print(' a[0] =', a[0])
print(' a[-1] =', a[-1])
print('Slicing also works just like strings:')
print(' a[1:3] =', a[1:3])
print(' a[3:] =', a[3:])
- Finding Elements
a = [ 2, 3, 5, 2, 6, 5, 5, 7, 5 ]
print('in, not in, count, and index all work just like strings:')
print(' ', 3 in a)
print(' ', 3 not in a)
print(' ', a.count(5))
print(' ', a.index(5))
- Adding Elements
- Using
append is destructive (modifies the list)
a = [ 2, 3 ]
a.append(7)
print(a)
- Using
+ is non-destructive (creates a new list)
a = [ 2, 3 ]
b = a + [ 7 ]
print(a)
print(b)
- Removing Elements
- Using
remove
a = [ 2, 3, 5, 4, 5 ]
print('a =', a)
a.remove(5)
print("After a.remove(5), a=", a)
a.remove(5)
print("After another a.remove(5), a=", a)
- Using
pop
a = [ 2, 3, 4, 5 ]
print('a =', a)
print('pop with no argument removes (pops) the last value:')
v = a.pop()
print(' We just popped:', v)
print(' And now a =', a)
print('pop with an argument removes the value at that index:')
v = a.pop(1)
print(' We just popped:', v)
print(' And now a =', a)
- Looping Over Lists
- Looping over items
a = [ 2, 3, 5, 7 ]
print('Here are the items in a:')
for item in a:
print(item)
- Looping over indexes
a = [ 2, 3, 5, 7 ]
print('Here are the items in a with their indexes:')
for i in range(len(a)):
print('a[', i, '] =', a[i])
- Example: The Locker Problem
def lockerProblem(lockers):
isOpen = [ False ] * (lockers+1)
students = lockers
for student in range(1,students+1):
for locker in range(student, lockers+1, student):
isOpen[locker] = not isOpen[locker]
openLockers = [ ]
for locker in range(1, lockers+1):
if isOpen[locker]:
openLockers.append(locker)
return openLockers
print(lockerProblem(2000))