Namedtuple In Python

Overview:

  • Like the tuple class, namedtuple is also a container in Python.
  • New tuple types can be created by simply passing the name of the type, using the class namedtuple.
  • With namedtuple two types of names are created for a tuple:
    • A name for the new tuple type
    • Names for the tuple fields
  • Often CSV files, Relational Database Tables have headers/column names for the data. Tuple objects with named fields map seamlessly to such data.
  • A namedtuple can be converted to a Python dict using the method _asdict().
  • The class namedtuple itself is derived from the Python tuple class.

Example – Making namedtuple instances from a CSV file:

The Python example reads the contents of the following CSV file and populates the namedtuple with the name AfterSalesRecord.

CSV File

# Example Python program that reads records from a CSV file

# and populates them into Python namedtuple instances

import collections as coll

import csv

 

# Create a new tuple type with the name AfterSalesRecord

SalesRecord = coll.namedtuple('AfterSalesRecord', 'make, units, totalusd');

 

# Create a CSV reader

csvReader   = csv.reader(open("car_aftersales.csv", "r"));

 

# Make a namedtuple for each record from the CSV file

print("Contents of the CSV file:");

for sales in map(SalesRecord._make, csvReader):

    print(sales.make, sales.units, sales.totalusd);

 

Output:

Contents of the CSV file:

make  units  totalusd

m1  5  35000

m2  7  32000

m3  2  12000

m4  4  15000

m5  10  67000

m6  8  64000

m7  5  50000

m8  4  80000

m8  4  80000

 


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