Pydictnest

Nothing fancy. Just a lightweight Python package for some basic work with nested dictionaries. Provides functions to set, get, check, flatten, and unflatten values in arbitrarily deep mappings, plus iteration over nested structures.

• Get and Set Get and set values based on a list of keys in nested mappings
• Check whether a nested path exists.
• Iterate over all (path, value) pairs in a nested mapping.
• Flatten a nested dict to a single-level dict with concatenated keys.
• Unflatten a flat dict back into a nested structure.

Installation

Install via pip with

pip install pydictnest

or from the newest source with

pip install git+https://github.com/MSallermann/pydictnest.git

You can also clone the repo and install locally

git clone https://github.com/MSallermann/pydictnest.git
cd pydictnest
pip install .

Usage

Should be quite obvious. Here is a small writeup (mostly take from the unit test):

from pydictnest import (
    set_nested, get_nested, has_nested,
    items_nested, flatten_dict, unflatten_dict
)

# Start with an empty dict
data = {}
set_nested(data, ['a', 'b', 'c'], 123)
# data == {'a': {'b': {'c': 123}}}

# Retrieve values
val = get_nested(data, ['a', 'b', 'c'])        # 123
missing = get_nested(data, ['x', 'y'], default=0) # 0

# Check existence
assert has_nested(data, ['a', 'b', 'c'])
assert not has_nested(data, ['a', 'z'])

# Iterate over all leaf nodes
for path, value in items_nested(data):
    print(path, value)
    # ['a', 'b', 'c'] 123

# Flatten and unflatten
nested = {'x': {'y': 1, 'z': {'w': 2}}, 'u': 3}
flat = flatten_dict(nested, sep='.')
# flat == {'x.y': 1, 'x.z.w': 2, 'u': 3}

roundtrip = unflatten_dict(flat, sep='.')
# roundtrip == nested

API Reference

set_nested(dictionary, keys, value, subdict_factory=dict)

Set a value at the specified nested key-path, creating sub-dicts with subdict_factory.

get_nested(dictionary, keys, default=None)

Retrieve a deep value, returning default if any key is missing.

has_nested(dictionary, keys)

Return True if a deep key-path exists, otherwise False.

items_nested(d, subkeys=[])

Yields (key_path, value) tuples for each leaf node in a nested mapping.

keys_nested(d)

Yields key_path for each leaf node in a nested mapping.

values_nested(d)

Yields value for each leaf node in a nested mapping.

flatten_dict(dictionary, sep='.', dict_factory=dict)

Convert a nested dict into a flat dict by joining keys with sep.

unflatten_dict(dictionary, sep='.', dict_factory=dict)

Reconstruct a nested mapping from a flat dict with joined keys.

Running Tests

This project uses pytest. To run the test suite:

pytest

Rationale

Not much of a rationale really. Needed this for a small project and wanted something lightweight.

Contributing

Make a PR if you want to contribute anything.

License

This project is licensed under the MIT License. See LICENSE for details.