Learn about Dictionaries datatype for Python: A dictionary is a data type similar to arrays but works with keys and values instead of indexes. 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 to address it.
For example, a database of phone numbers could be stored using a dictionary like this:
phonebook = {}
phonebook["John"] = 555477566
phonebook["Jack"] = 555377264
phonebook["Jill"] = 555662781
print(phonebook)
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Alternatively, a dictionary can be initialized with the same values in the following notation:
phonebook = {
"John" : 938477566,
"Jack" : 938377264,
"Jill" : 947662781
}
print(phonebook)
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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 = {"John" : 938477566,"Jack" : 938377264,"Jill" : 947662781}
for name, number in phonebook.items():
print("Phone number of %s is %d" % (name, number))
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Removing a value
To remove a specified index, use either one of the following notations:
phonebook = {
"John" : 938477566,
"Jack" : 938377264,
"Jill" : 947662781
}
del phonebook["John"]
print(phonebook)
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or:
phonebook = {
"John" : 938477566,
"Jack" : 938377264,
"Jill" : 947662781
}
phonebook.pop("John")
print(phonebook)
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Exercise
Add “Jake” to the phonebook with the phone number 938273443, and remove Jill from the phonebook.
#this is the answer code. use online compiler below to complete the assignment on your own.
phonebook = {
"John" : 938477566,
"Jack" : 938377264,
"Jill" : 947662781
}
# write your code here
phonebook["Jake"] = 938273443
del phonebook["Jill"]
# testing code
if "Jake" in phonebook:
print("Jake is listed in the phonebook.")
if "Jill" not in phonebook:
print("Jill is not listed in the phonebook.")
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