Home Backend Development Python Tutorial How Can I Efficiently Create a Single Dictionary from a CSV File of Key-Value Pairs?

How Can I Efficiently Create a Single Dictionary from a CSV File of Key-Value Pairs?

Nov 19, 2024 am 06:18 AM

How Can I Efficiently Create a Single Dictionary from a CSV File of Key-Value Pairs?

Creating a Unified Dictionary from a CSV File Consisting of Unique Key-Value Pairs

When handling CSV files, one common task is to create dictionaries where each row represents a unique key-value pair. While the 'csv.DictReader' class provides a convenient way to iterate through such files row-by-row, creating a unified dictionary requires a different approach.

The provided code attempts to construct a dictionary within the nested loop, leading to the 'ValueError' due to attempting to unpack multiple values with only two expected. To address this issue, the syntax should be slightly modified:

Python 3:

import csv

with open('coors.csv', mode='r') as infile:
    reader = csv.reader(infile)
    with open('coors_new.csv', mode='w') as outfile:
        writer = csv.writer(outfile)
        mydict = {rows[0]: rows[1] for rows in reader}
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Python 2:

import csv

with open('coors.csv', mode='r') as infile:
    reader = csv.reader(infile)
    with open('coors_new.csv', mode='w') as outfile:
        writer = csv.writer(outfile)
        mydict = dict((rows[0], rows[1]) for rows in reader)
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This revised syntax correctly iterates through the CSV file, extracting the key from the first column and the value from the second column for each row. The result is a single dictionary where the keys are unique and sourced from the first column, and the values are sourced from the second column. This approach consolidates all key-value pairs into a comprehensive dictionary.

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