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Dictionaries in Python, are used to store data values in key:value pairs. Each value stored in a dictionary can be accessed using a key, which is any type of object (a string, a number, a list, etc.) instead of using its index on address it.

For example, a database of phone numbers could be stored using a dictionary like this:

phonebook = {} phonebook["John"] = 938477566 phonebook["Jack"] = 938377264 phonebook["Jill"] = 947662781 print(phonebook)

Alternatively, a dictionary can be initialized with the same values in the following notation:

phonebook = { "John" : 938477566, "Jack" : 938377264, "Jill" : 947662781 } print(phonebook)

Iterating over dictionaries

Dictionaries can be iterated over, just like a list. However, a dictionary, unlike a list, does not keep the order of the values stored in it. To iterate over key value pairs, use the following syntax:

phonebook = {"Raymond" : 938477566,"Ivan" : 938377264,"Rich" : 947662781} for name, number in phonebook.items(): print("Phone number of %s is %d" % (name, number))

Removing a value

To remove a specified index, use either one of the following notations:

phonebook = { "Raymond" : 938477566, "Ivan" : 938377264, "Rich" : 947662781 } del phonebook["Raymond"] print(phonebook)

OR:

phonebook = { "Raymond" : 938477566, "Ivan" : 938377264, "Rich" : 947662781 } phonebook.pop("Raymond") print(phonebook)

Exercise

Add "Mike" to the phonebook with the phone number 938273443, and remove Rich from the phonebook.

phonebook = { "Raymond" : 938477566, "Ivan" : 938377264, "Rich" : 947662781 } # your code goes here
# testing code if "Mike" in phonebook: print("Mike is listed in the phonebook.")
if "Rich" not in phonebook: print("Rich is not listed in the phonebook.")
phonebook = { "Raymond" : 938477566, "Ivan" : 938377264, "Rich" : 947662781 }
# your code goes here phonebook["Mike"] = 938273443 del phonebook["Rich"]
# testing code if "Mike" in phonebook: print("Mike is listed in the phonebook.")
if "Rich" not in phonebook: print("Rich is not listed in the phonebook.")
test_output_contains("Mike is listed in the phonebook.") test_output_contains("Rich is not listed in the phonebook.") success_msg("Excellent!")

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