Dictionary Methods in Python 

 

Dictionary Methods in Python

Python has build in methods to work with dictionaries.

clear()
copy()
fromkeys()
get()
items()
keys()
pop()
popitem()
setdefault()
update()
values()

clear() dictionary.clear()
Removes all the elements from the dictionary 

phonebook = {'John': '000001', 'Peter': '000002', 'Rachel': '000003'}

phonebook.clear()

print(phonebook)
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{}

 

copy() dictionary.copy()
Returns a copy of the dictionary 

mydict= {'key1': 0, 'key2': 0, 'key3': 0}

newdict= mydict.copy()

print(newdict)
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{'key1': 0, 'key2': 0, 'key3': 0}

 

fromkeys() dict.fromkeys(keys, value)
Returns a dictionary with the specified keys and value 

key = ('key1', 'key2', 'key3')
value = 0

mydict= dict.fromkeys(key, value)

print(mydict)
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/usr/bin/python3.8 https://viteac.blogspot.com

{'key1': 0, 'key2': 0, 'key3': 0}

 

get() dictionary.get(keyname, value)
Returns the value of the specified key 

phonebook = {'John': '000001', 'Peter': '000002', 'Rachel': '000003'}

number = phonebook.get('Peter')

print(number)
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/usr/bin/python3.8 https://viteac.blogspot.com

000002

 

items() dictionary.items()
Returns a list containing a tuple for each key value pair 

phonebook = {'John': '000001', 'Peter': '000002', 'Rachel': '000003'}

x = phonebook.items()

print(x)
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/usr/bin/python3.8 https://viteac.blogspot.com

dict_items([('John', '000001'), ('Peter', '000002'), ('Rachel', '000003')])

 

keys() dictionary.keys()
Returns a list containing the dictionary's keys 

phonebook = {'John': '000001', 'Peter': '000002', 'Rachel': '000003'}

x = phonebook.keys()

print(x)
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/usr/bin/python3.8 https://viteac.blogspot.com

dict_keys(['John', 'Peter', 'Rachel'])

 

pop() dictionary.pop(keyname, defaultvalue)
Removes the element with the specified key

phonebook = {'John': '000001', 'Peter': '000002', 'Rachel': '000003'}

phonebook.pop("John")

print(phonebook)
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/usr/bin/python3.8 https://viteac.blogspot.com

{'Peter': '000002', 'Rachel': '000003'}

popitem() dictionary.popitem()
Removes the last inserted key-value pair 

phonebook = {'John': '000001', 'Peter': '000002', 'Rachel': '000003'}

phonebook.popitem()

print(phonebook)
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/usr/bin/python3.8 https://viteac.blogspot.com

{'John': '000001', 'Peter': '000002'}

 

setdefault() dictionary.setdefault(keyname, value)
Returns the value of the specified key. If the key does not exist: insert the key, with the specified value 

phonebook = {'John': '000001', 'Peter': '000002', 'Rachel': '000003'}

s= phonebook.setdefault('Rachel')

print(s)
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/usr/bin/python3.8 https://viteac.blogspot.com

000003

 

If the key doesn't exist setdefault() will insert the key with value NONE

phonebook = {'John': '000001', 'Peter': '000002', 'Rachel': '000003'}

s= phonebook.setdefault('Marcin')

print(phonebook)
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/usr/bin/python3.8 https://viteac.blogspot.com

{'John': '000001', 'Peter': '000002', 'Rachel': '000003', 'Marcin': None}

You can also add the key with value if doesn't exist.

phonebook = {'John': '000001', 'Peter': '000002', 'Rachel': '000003'}

s= phonebook.setdefault('Marcin', 1234567)

print(phonebook)
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/usr/bin/python3.8 https://viteac.blogspot.com

{'John': '000001', 'Peter': '000002', 'Rachel': '000003', 'Marcin': 1234567}

update() dictionary.update(iterable)
Updates the dictionary with the specified key-value pairs 

phonebook = {'Name': 'John', 'PhoneN0': '000002'}

phonebook.update({'Email': 'johnseamail@longjohn.com'})

print(phonebook)
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/usr/bin/python3.8 https://viteac.blogspot.com

{'Name': 'John', 'PhoneN0': '000002', 'Email': 'johnseamail@longjohn.com'}

 

values() dictionary.values()
Returns a list of all the values in the dictionary 

phonebook = {'Name': 'John', 'PhoneN0': '000002', 'Email': 'johnseamail@longjohn.com'}

x = phonebook.values()

print(x)
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/usr/bin/python3.8 https://viteac.blogspot.com

dict_values(['John', '000002', 'johnseamail@longjohn.com'])