How to Write Python Dict to CSV Columns? (Keys & Values Columns)

4.7/5 - (3 votes)
Write Python Dict to CSV Columns

Method 1: CSV Writer

To write a Python dictionary in a CSV file as a column, i.e., a single (key, value) pair per row, use the following three steps:

  • Open the file in writing mode and using the newline='' argument to prevent blank lines.
  • Create a CSV writer object.
  • Iterate over the (key, value) pairs of the dictionary using the dict.items() method.
  • Write one (key, value) tuple at a time by passing it in the writer.writerow() method.

Here’s the code example:

import csv


# Create a dictionary of key-value pairs
data = {'A':42, 'B':41, 'C':40}

# Open the file in writing mode (no blank lines)
with open('my_file.csv', 'w', newline='') as f:

    # Create a CSV writer object
    writer = csv.writer(f)

    # Write one key-value tuple per row
    for row in data.items():
        writer.writerow(row)

Your output CSV file (column dict) looks like this:

Example 2: Vanilla Python

The shortest, most concise, and easiest way to write a dictionary as a CSV file using the dict keys as first column and the dict values as second column is to use normal Python file handling.

  • First, open the file in writing mode.
  • Second, iterate over all (key, value) pairs.
  • Third, write each key value pair in one line using the standard Python file writing method.

Here’s the concrete example:

import csv


data = {'A':42, 'B':41, 'C':40}

with open('my_file.csv', 'w') as f:
    for key, value in data.items():
        f.write(f'{key},{value}\n')
        

Again, the resulting CSV file (column dict) looks like this:

If you need a header in the column CSV file, you can do that with another extra call of file.write('Col_A,Col_B\n') just before starting to iterate over the dictionary.

🌍 Related Resource: 7 Best Ways to Convert Dict to CSV in Python


Programmer Humor

❓ Question: Why do programmers always mix up Halloween and Christmas?
❗ Answer: Because Oct 31 equals Dec 25.

(If you didn’t get this, read our articles on the oct() and int() Python built-in functions!)