Python supports a type of container like dictionaries called “namedtuples()” present in module, “collection“. Like dictionaries they contain keys that are hashed to a particular value. But on contrary, it supports both access from key value and iteration, the functionality that dictionaries lack.
Operations on namedtuple() :
1. Access by index : The attribute values of namedtuple() are ordered and can be accessed using the index number unlike dictionaries which are not accessible by index.
2. Access by keyname : Access by keyname is also allowed as in dictionaries.
3. using getattr() :- This is yet another way to access the value by giving namedtuple and key value as its argument.
# Python code to demonstrate namedtuple() and # Access by name, index and getattr() # importing "collections" for namedtuple() import collections # Declaring namedtuple() Student = collections.namedtuple('Student',['name','age','DOB']) # Adding values S = Student('Nandini','19','2541997') # Access using index print ("The Student age using index is : ",end ="") print (S[1]) # Access using name print ("The Student name using keyname is : ",end ="") print (S.name) # Access using getattr() print ("The Student DOB using getattr() is : ",end ="") print (getattr(S,'DOB')) |
Output :
The Student age using index is : 19 The Student name using keyname is : Nandini The Student DOB using getattr() is : 2541997
1. _make() :- This function is used to return a namedtuple() from the iterable passed as argument.
2. _asdict() :- This function returns the OrdereDict() as constructed from the mapped values of namedtuple().
3. using “**” (double star) operator :- This function is used to convert a dictionary into the namedtuple().
# Python code to demonstrate namedtuple() and # _make(), _asdict() and "**" operator # importing "collections" for namedtuple() import collections # Declaring namedtuple() Student = collections.namedtuple('Student',['name','age','DOB']) # Adding values S = Student('Nandini','19','2541997') # initializing iterable li = ['Manjeet', '19', '411997' ] # initializing dict di = { 'name' : "Nikhil", 'age' : 19 , 'DOB' : '1391997' } # using _make() to return namedtuple() print ("The namedtuple instance using iterable is : ") print (Student._make(li)) # using _asdict() to return an OrderedDict() print ("The OrderedDict instance using namedtuple is : ") print (S._asdict()) # using ** operator to return namedtuple from dictionary print ("The namedtuple instance from dict is : ") print (Student(**di)) |
Output :
The namedtuple instance using iterable is :
Student(name='Manjeet', age='19', DOB='411997')
The OrderedDict instance using namedtuple is :
OrderedDict([('name', 'Nandini'), ('age', '19'), ('DOB', '2541997')])
The namedtuple instance from dict is :
Student(name='Nikhil', age=19, DOB='1391997')
1. _fields :- This function is used to return all the keynames of the namespace declared.
2. _replace() :- This function is used to change the values mapped with the passed keyname.
# Python code to demonstrate namedtuple() and # _fields and _replace() # importing "collections" for namedtuple() import collections # Declaring namedtuple() Student = collections.namedtuple('Student',['name','age','DOB']) # Adding values S = Student('Nandini','19','2541997') # using _fields to display all the keynames of namedtuple() print ("All the fields of students are : ") print (S._fields) # using _replace() to change the attribute values of namedtuple print ("The modified namedtuple is : ") print(S._replace(name = 'Manjeet')) |
Output :
All the fields of students are :
('name', 'age', 'DOB')
The modified namedtuple is :
Student(name='Manjeet', age='19', DOB='2541997')
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