How to pretty print nested dictionaries?

ghz 3months ago ⋅ 41 views

How can I pretty print a dictionary with depth of ~4 in Python? I tried pretty printing with pprint(), but it did not work:

import pprint 
pp = pprint.PrettyPrinter(indent=4)
pp.pprint(mydict)

I simply want an indentation ("\t") for each nesting, so that I get something like this:

key1
    value1
    value2
    key2
       value1
       value2

etc.

How can I do this?

Answers

To achieve pretty-printing of a dictionary with custom indentation for nested levels in Python, pprint might not always offer the flexibility you need for deep nesting. Instead, you can use a custom function to handle indentation and formatting according to your specific requirements.

Here’s a function that will pretty-print a dictionary with nested levels and use tabs ("\t") for indentation:

def pretty_print_dict(d, indent=0):
    """
    Recursively prints a dictionary with custom indentation for each level.

    Parameters:
    - d: Dictionary to be printed.
    - indent: The current level of indentation (used for recursion).
    """
    for key, value in d.items():
        print("\t" * indent + str(key))
        if isinstance(value, dict):
            pretty_print_dict(value, indent + 1)
        elif isinstance(value, list):
            for item in value:
                if isinstance(item, dict):
                    pretty_print_dict(item, indent + 1)
                else:
                    print("\t" * (indent + 1) + str(item))
        else:
            print("\t" * (indent + 1) + str(value))

# Example usage
mydict = {
    'key1': {
        'key1.1': 'value1.1',
        'key1.2': {
            'key1.2.1': 'value1.2.1',
            'key1.2.2': ['value1.2.2', {'key1.2.2.1': 'value1.2.2.1'}]
        }
    },
    'key2': 'value2'
}

pretty_print_dict(mydict)

Explanation

  1. Function Definition: pretty_print_dict(d, indent=0):

    • d: The dictionary to print.
    • indent: The current level of indentation.

  2. Loop through Items:

    • Keys: Print the key with the current level of indentation.
    • Values: Handle values based on their type:
      • Dicts: Recursively call pretty_print_dict with increased indentation.
      • Lists: Iterate over the list. For dictionary items within the list, call pretty_print_dict recursively. For other types, print them with increased indentation.
      • Other Types: Print values with increased indentation.

  3. Example Usage: The mydict dictionary contains nested dictionaries and lists to demonstrate the function’s capability to handle different structures.

Output

For the example dictionary, the output will be:

key1
    key1.1
        value1.1
    key1.2
        key1.2.1
            value1.2.1
        key1.2.2
            value1.2.2
            key1.2.2.1
                value1.2.2.1
key2
    value2

This approach gives you control over the formatting and handles complex nesting and list elements in a dictionary. You can adjust the indentation level or format as needed.

#python