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Added lesson 7
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‎lesson07/dictionaries.py‎

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# Dictionaries
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band = {
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"vocals": "Plant",
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"guitar": "Page"
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}
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band2 = dict(vocals="Plant", guitar="Page")
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print(band)
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print(band2)
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print(type(band))
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print(len(band))
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# Access items
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print(band["vocals"])
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print(band.get("guitar"))
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# list all keys
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print(band.keys())
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# list all values
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print(band.values())
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# list of key/value pairs as tuples
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print(band.items())
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# verify a key exists
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print("guitar" in band)
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print("triangle" in band)
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# Change values
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band["vocals"] = "Coverdale"
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band.update({"bass": "JPJ"})
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print(band)
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# Remove items
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print(band.pop("bass"))
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print(band)
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band["drums"] = "Bonham"
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print(band)
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print(band.popitem()) # tuple
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print(band)
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# Delete and clear
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band["drums"] = "Bonham"
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del band["drums"]
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print(band)
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band2.clear()
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print(band2)
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del band2
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# Copy dictionaries
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# band2 = band # create a reference
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# print("Bad copy!")
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# print(band2)
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# print(band)
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# band2["drums"] = "Dave"
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# print(band)
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band2 = band.copy()
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band2["drums"] = "Dave"
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print("Good copy!")
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print(band)
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print(band2)
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# or use the dict() constructor function
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band3 = dict(band)
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print("Good copy!")
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print(band3)
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# Nested dictionaries
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member1 = {
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"name": "Plant",
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"instrument": "vocals"
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}
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member2 = {
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"name": "Page",
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"instrument": "guitar"
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}
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band = {
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"member1": member1,
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"member2": member2
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}
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print(band)
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print(band["member1"]["name"])
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# Sets
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nums = {1, 2, 3, 4}
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nums2 = set((1, 2, 3, 4))
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print(nums)
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print(nums2)
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print(type(nums))
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print(len(nums))
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# No duplicate allowed
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nums = {1, 2, 2, 3}
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print(nums)
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# True is a dupe of 1, False is a dupe of zero
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nums = {1, True, 2, False, 3, 4, 0}
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print(nums)
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# check if a value is in a set
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print(2 in nums)
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# but you cannot refer to an element in the set with an index position or a key
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# Add a new element to a set
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nums.add(8)
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print(nums)
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# Add elements from one set to another
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morenums = {5, 6, 7}
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nums.update(morenums)
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print(nums)
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# you can use update with lists, tuples, and dictionaries, too.
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# Merge two sets to create a new set
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one = {1, 2, 3}
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two = {5, 6, 7}
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mynewset = one.union(two)
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print(mynewset)
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# Keep only the duplicates
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one = {1, 2, 3}
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two = {2, 3, 4}
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one.intersection_update(two)
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print(one)
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# Keep everything except the duplicates
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one = {1, 2, 3}
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two = {2, 3, 4}
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one.symmetric_difference_update(two)
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print(one)

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