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This tutorial will show you how to write a dictionary variable to a csv file in Python.

csvWriting a dictionary to a CSV file using the module in Python

The Python module csvcontains tools and functions for manipulating csv files. There are two simple methods that can be used to write a dictionary to a csv file. writer()and DictWriter().

The functions of these two methods are similar, the only difference is DictWriter()that is a wrapper class that contains more functions.

Let's set up an initial example with a dictionary with a few key-value pairs:

dct = {"Name": "John", "Age": "23", "Country": "USA"}

In the first example, we use writer()to access a new csv file and insert a dictionary into it.

import csv

dct = {"Name": "John", "Age": "23", "Country": "USA"}

with open("dct.csv", "w") as f:
    writer = csv.writer(f)
    for k, v in dct.items():
        writer.writerow([k, v])

Since the file access type is w, the contents of the csv file dct.csvwill be overwritten with the new changes. If the file does not exist then it will be automatically created in the same directory.

The contents of the csv file will be output:

Since there is only one dictionary entry, the layout of the csv file contains all the keys in the first column and the values ​​in the second column.

Example using dictionary array

This is an example for a single dictionary. What if you want to insert multiple dictionaries into a csv file?

In this example, we will use the function DictWriter()to write to a csv file. The CSV layout from the first example also needs to be changed because there are multiple values ​​for the same key.

The first line should contain the key labels, and the following lines will contain the values ​​for each dictionary entry.

First, declare an array of dictionaries with the same key values.

dct_arr = [
    {"Name": "John", "Age": "23", "Country": "USA"},
    {"Name": "Jose", "Age": "44", "Country": "Spain"},
    {"Name": "Anne", "Age": "29", "Country": "UK"},
    {"Name": "Lee", "Age": "35", "Country": "Japan"},
]

Now write this array of dictionaries to a csv file using csvthe module .DictWriter()

import csv

labels = ["Name", "Age", "Country"]
dct_arr = [
    {"Name": "John", "Age": "23", "Country": "USA"},
    {"Name": "Jose", "Age": "44", "Country": "Spain"},
    {"Name": "Anne", "Age": "29", "Country": "UK"},
    {"Name": "Lee", "Age": "35", "Country": "Japan"},
]

try:
    with open("csv_dct.csv", "w") as f:
        writer = csv.DictWriter(f, fieldnames=labels)
        writer.writeheader()
        for elem in dct_arr:
            writer.writerow(elem)
except IOError:
    print("I/O error")

DictWriter()The arguments in fieldnamesare assigned to a variable labels, which is an array of dictionaries whose keys are arrays of labels.

It is also a good practice to wrap your file manipulation code with exception handling ( try ... except) to prevent external errors or incompatibilities with the file writing process.

Output:

All in all, csvthe module contains all the necessary functions and tools to write a dictionary to a csv file. This can be easily achieved using the functions writer()and .DictWriter()

Also note that you should wrap the blocks that manipulate files with exception handling to ensure that you catch the IO error before it corrupts anything.