Python pprint: Pretty Printing Complex Data Structures

from pprint import pprint
 
data = {
    'users': [
        {'name': 'Alice', 'age': 30, 'roles': ['admin', 'editor']},
        {'name': 'Bob', 'age': 25, 'roles': ['viewer']},
    ],
    'metadata': {'version': '1.0', 'created': '2024-01-01'}
}
 
# Standard print (hard to read)
print(data)
# {'users': [{'name': 'Alice', 'age': 30, 'roles': ['admin', 'editor']}, ...
 
# Pretty print (readable)
pprint(data)
# {'metadata': {'created': '2024-01-01', 'version': '1.0'},
#  'users': [{'age': 30, 'name': 'Alice', 'roles': ['admin', 'editor']},
#            {'age': 25, 'name': 'Bob', 'roles': ['viewer']}]}

from pprint import pprint
 
data = {'key1': 'value1', 'key2': 'value2', 'key3': 'value3'}
 
# Default width (80)
pprint(data)
# {'key1': 'value1', 'key2': 'value2', 'key3': 'value3'}
 
# Narrow width (forces wrapping)
pprint(data, width=40)
# {'key1': 'value1',
#  'key2': 'value2',
#  'key3': 'value3'}
 
# Very narrow
pprint(data, width=1)
# {'key1': 'value1',
#  'key2': 'value2',
#  'key3': 'value3'}

from pprint import pprint
 
nested = {
    'level1': {
        'level2': {
            'level3': {
                'level4': 'deep value'
            }
        }
    }
}
 
# Show only 2 levels deep
pprint(nested, depth=2)
# {'level1': {'level2': {...}}}
 
# Full depth (default)
pprint(nested)
# {'level1': {'level2': {'level3': {'level4': 'deep value'}}}}

from pprint import pprint
 
data = {'a': [1, 2, 3], 'b': [4, 5, 6]}
 
# Default indent (1)
pprint(data, width=20)
# {'a': [1, 2, 3],
#  'b': [4, 5, 6]}
 
# Larger indent
pprint(data, width=20, indent=4)
# {'a': [1, 2, 3],
#     'b': [4, 5, 6]}

from pprint import pformat
 
data = {'name': 'Alice', 'scores': [95, 87, 92]}
 
# Get formatted string (don't print)
formatted = pformat(data)
print(type(formatted))  # <class 'str'>
 
# Use in logging
import logging
logging.info("Data: %s", pformat(data))
 
# Use in f-strings
message = f"Received:\n{pformat(data)}"

from pprint import PrettyPrinter
 
# Create configured printer
pp = PrettyPrinter(indent=2, width=60, depth=3)
 
data = {'key': 'value', 'nested': {'a': 1, 'b': 2}}
 
pp.pprint(data)
formatted = pp.pformat(data)

from pprint import pprint
 
items = list(range(20))
 
# Default (one per line when it doesn't fit)
pprint(items, width=40)
# [0,
#  1,
#  2,
#  ...
 
# Compact (squeeze multiple per line)
pprint(items, width=40, compact=True)
# [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11,
#  12, 13, 14, 15, 16, 17, 18, 19]

from pprint import pprint
 
data = {'z': 1, 'a': 2, 'm': 3}
 
# Default: sorted keys (Python 3.8+)
pprint(data)
# {'a': 2, 'm': 3, 'z': 1}
 
# Preserve insertion order
pprint(data, sort_dicts=False)
# {'z': 1, 'a': 2, 'm': 3}

from pprint import pprint
 
def process_api_response(response):
    # Debug: see what we got
    print("Response received:")
    pprint(response, depth=2)
    
    # Process...
    return response['data']
 
# In debugger or REPL
response = {'data': {'users': [...], 'meta': {...}}}
pprint(response)

from pprint import pprint
 
class User:
    def __init__(self, name, email):
        self.name = name
        self.email = email
    
    def __repr__(self):
        return f"User(name={self.name!r}, email={self.email!r})"
 
users = [User('Alice', 'alice@example.com'), User('Bob', 'bob@example.com')]
 
pprint(users)
# [User(name='Alice', email='alice@example.com'),
#  User(name='Bob', email='bob@example.com')]

from pprint import pformat
import logging
 
logging.basicConfig(level=logging.DEBUG)
logger = logging.getLogger(__name__)
 
def log_response(response: dict):
    """Log API response in readable format."""
    logger.debug("API Response:\n%s", pformat(response))
 
# Usage
log_response({'status': 'ok', 'data': {'items': [1, 2, 3]}})

from pprint import pprint
 
data = {'config': {'debug': True, 'options': ['a', 'b', 'c']}}
 
# Write to file
with open('debug_output.txt', 'w') as f:
    pprint(data, stream=f)
 
# Or use pformat
with open('debug_output.txt', 'w') as f:
    f.write(pformat(data))

import json
from pprint import pformat
 
data = {'users': [{'name': 'Alice'}, {'name': 'Bob'}]}
 
# JSON (no trailing commas, double quotes)
print(json.dumps(data, indent=2))
# {
#   "users": [
#     {"name": "Alice"},
#     {"name": "Bob"}
#   ]
# }
 
# pprint (Python syntax, single quotes)
print(pformat(data))
# {'users': [{'name': 'Alice'}, {'name': 'Bob'}]}

from pprint import pformat
 
def load_config(path: str) -> dict:
    config = {'loaded': True, 'settings': {}}  # Load from file
    print(f"Loaded config from {path}:\n{pformat(config)}")
    return config

from pprint import pformat
 
def test_api_response():
    response = fetch_api()
    
    assert 'data' in response, f"Missing 'data' in:\n{pformat(response)}"

# In your Python REPL config (~/.pythonrc.py)
from pprint import pprint as pp
 
# Now use pp() for quick inspection
# >>> pp(some_complex_dict)