empty = {}                         # create an empty dictionary
          
fruit = {"orange": "a sweet, orange, citrus fruit",
         "apple": "good for making cider",
         "lemon": "a sour, yellow citrus fruit",
         "grape": "a small, sweet fruit growing in bunches",
         "lime": "a sour, green citrus fruit",
         "smelly fruit": "horrible smelly fruit"}
         
print(fruit['orange'])

sports = { "outdoor": "football", "indoor": "squash", "underground": "caving" }
len(sports)

fruit.keys()                         # returns all keys
fruit.values()                       # returns all values
fruit.items()                        # returns both keys and values

fruit.get('orange')                  # return value associated with key 'orange'
fruit.get('banana', 'No Banana')     # if no banana key is found, return string 'No Banana'

'orange' in fruit                    # True
'banana' in fruit                    # False

del(fruit['orange'])

fruits = fruit.copy()

Note: makes a shallow copy of a dictionary

z = {1: 'One', 2: 'Two'}
x = {0: 'zero', 1: 'one'}
x.update(z)                          # results in {0: 'zero', 1: 'One', 2: 'Two'}

Note: combines the entries of two dictionaries

fruit = {"orange": "a sweet, orange, citrus fruit",
         "apple": "good for making cider",
         "lemon": "a sour, yellow citrus fruit",
         "grape": "a small, sweet fruit growing in bunches",
         "lime": "a sour, green citrus fruit",
         "smelly fruit": "horrible smelly fruit"}

print(fruit.get('orange'))
print(fruit.get('xxxx', 'banana'))

# add to dictionary
fruit["pear"] = "an odd shape apple"

# overwrite element
fruit["lime"] = "great with tequila"

# delete a element
del fruit["smelly fruit"]

print(fruit)
print(fruit["lemon"])
print(fruit["lime"])

for key in fruit:
    print("{}: {}".format(key, fruit[key]))

for key, value in fruit.items():
    print("{}: {}".format(key, value))

print("\nOrdered list: ")
for key in sorted(list(fruit.keys())):
    print("\t{}: {}".format(key, fruit[key]))

# get tuples from dictionary, you can also go the other way
f_tuple = tuple(fruit.items())
print(f_tuple)

print("\n---------------------------------------------------------------------")

bike = {"make": "Honda", "model": "250 dream", "color": "red", "engine_size": 250}
print(bike)
print(bike["engine_size"])

print("\n---------------------------------------------------------------------")

locations = {0: {"desc": "You are sitting in front of a computer learning Python",
                 "exits": {},
                 "namedExits": {}},
             1: {"desc": "You are standing at the end of a road before a small brick building",
                 "exits": {"W": 2, "E": 3, "N": 5, "S": 4, "Q": 0},
                 "namedExits": {"2": 2, "3": 3, "5": 5, "4": 4}},
             2: {"desc": "You are at the top of a hill",
                 "exits": {"N": 5, "Q": 0},
                 "namedExits": {"5": 5}},
             3: {"desc": "You are inside a building, a well house for a small stream",
                 "exits": {"W": 1, "Q": 0},
                 "namedExits": {"1": 1}},
             4: {"desc": "You are in a valley beside a stream",
                 "exits": {"N": 1, "W": 2, "Q": 0},
                 "namedExits": {"1": 1, "2": 2}},
             5: {"desc": "You are in the forest",
                 "exits": {"W": 2, "S": 1, "Q": 0},
                 "namedExits": {"2": 2, "1": 1}}
             }

vocabulary = {"QUIT": "Q",
              "NORTH": "N",
              "SOUTH": "S",
              "EAST": "E",
              "WEST": "W",
              "ROAD": "1",
              "HILL": "2",
              "BUILDING": "3",
              "VALLEY": "4",
              "FOREST": "5"}

loc = 1
while True:
    availableExits = ", ".join(locations[loc]["exits"].keys())

    print(locations[loc]["desc"])

    if loc == 0:
        break
    else:
        allExits = locations[loc]["exits"].copy()
        allExits.update(locations[loc]["namedExits"])

    direction = input("Available exits are " + availableExits + ": ").upper()
    print()

    # Parse the user input, using our vocabulary dictionary if necessary
    if len(direction) > 1:  # more than 1 letter, so check vocab
        words = direction.split()
        for word in words:
            if word in vocabulary:  # does it contain a word we know?
                direction = vocabulary[word]
                break

    if direction in allExits:
        loc = allExits[direction]
    else:
        print("You cannot go in that direction")

matrix = {(0, 0): 3, (0, 2): -2, (0, 3): 11,
(1, 1): 9, (2, 1): 7, (3, 3): -5}

# you can use the below to obtain a element
if (rownum, colnum) in matrix:
    element = matrix[(rownum, colnum)]
else:
    element = 0

# same as above but easier
element = matrix.get((rownum, colnum), 0)

sole_cache = {}
          
def sole(m, n, t):
    if (m, n, t) in sole_cache:
        return sole_cache[(m, n, t)]                             # return the already cached result
    else:
        # . . . do some time-consuming calculations . . .
        sole_cache[(m, n, t)] = result
        return result