######## string #########
print('--- review string ---')
s = 'a,b,c,d,e'
print(s[2])
print(s.split(','), list(s))
print(s.split())
print(s.split(' '))
print(s.split('@'))
print(s[1:3])
print(s[:3])
print(s[3:])
print(s[2], s[-1], s[len(s)-1])
print("s[2:2] shouldn't get anything", s[2:2])


######## list #########
print('--- review list ---')
x = [3]
print(x)
x[0] = 9
print(x)
print(x * 2)        # repeat 2 times
x += ['12', '34', '5']
x[1] = '9'
print(x)
print(x[2], x[-1], x[len(x)-1])  # access element in list as lst[index]
print(x[1:2])        # get a copy of a slice of x from index 1 up to index 2 (not include index 2)
print("x[2:2] shouldn't get anything", x[2:2])
print(x)             # notice, x does not change
print(x.pop())       # pop() returns the value of the last item and remove it from the list
print('after pop()', x)
x.append(555)        # add item to the end of the list
print('after append(555)', x)
print(x.append(666)) # append() returns None and thus will print None
print('after append(666)', x)   # notice mix type elements in list
print('--- list can be iterated, sliced, and mutated ---\n')
# remove() removes an item by value from the list but not return anything
# therefore, if we call print(x.remove(555), it displays None
print(x.remove(555))
# since remove(value) looks for the given value and remove it from the list,
# try removing a value that's not in a list and see what exception occurs
# (note: remove by value of the item, *not* by index
print(x)


##############

print('--- nested lists ---')
lst = ['A', [0, 1], ['B', [2, 3], ['C', [4, 5]]]]
# what do the following code produce?
print(lst[1])
print(lst[1][0])
print(lst[1][1])

print(lst[2])
print(lst[2][0])
print(lst[2][1])
print(lst[2][2])

print(lst[2][2][0])
print(lst[2][2][1])
print(lst[2][2][1][0])
print(lst[2][2][1][1])



######## dict #########

print('--- review dict ---')
x = {1:2, 2:3, 3:4}
x[1] = 9
print('x =', x)
# print('can\'t slice a dict', x[2:3])

x[1] = 33     # re-assign value associated with key=1
print('after reassigment, x =', x)
print('x[2] =', x[2])   # access element in dict whose key=2

print('x.keys() =', x.keys())        # access all keys in dict
# keys() return a special dict_keys type (which looks similar to list but attached with dict_keys keyword)

print('x.values() =', x.values())    # access all values in dict
# values() return a special dict_values type (which looks similar to list but attached with dict_values keyword)

print('x.items() =', x.items())      # access all key-value pairs in dict
# items() return a special dict_items type (which looks similar to list of pairs/tuples but attached with dict_items keyword)

print(4 in x, 4 in x.keys(), 4 in x.items(), 4 in x.values())
  # Notice that when working with dict, python looks at keys in dict
  # therefore, the first 3 checking for 4 will result in False.
  # The last checking explicitly says look in values of dict.
print('--- dict can be iterated, and mutated ---\n')


print('--- don\'t forget to consider casting ---')
x = 12345
# print(list(x))    # what's wrong?

x = 12345
print(list(str(x)))
# x = '12345'
# print(list(x))

x = '12345'
# print(dict(x))     # what's wrong?