smart_importer

https://github.com/beancount/smart_importer

.. image:: https://github.com/beancount/smart_importer/actions/workflows/ci.yml/badge.svg?branch=main :target: https://github.com/beancount/smart_importer/actions?query=branch%3Amain

Augments Beancount <http://furius.ca/beancount/>__ importers with machine learning functionality.

Status

Working protoype, development status: beta

Installation

The smart_importer can be installed from PyPI:

.. code:: bash

pip install smart_importer

Quick Start

This package provides import hooks that can modify the imported entries. When running the importer, the existing entries will be used as training data for a machine learning model, which will then predict entry attributes.

The following example shows how to apply the PredictPostings hook to an existing CSV importer:

.. code:: python

from beancount.ingest.importers import csv
from beancount.ingest.importers.csv import Col

from smart_importer import apply_hooks, PredictPostings


class MyBankImporter(csv.Importer):
    '''Conventional importer for MyBank'''

    def __init__(self, *, account):
        super().__init__(
            {Col.DATE: 'Date',
             Col.PAYEE: 'Transaction Details',
             Col.AMOUNT_DEBIT: 'Funds Out',
             Col.AMOUNT_CREDIT: 'Funds In'},
            account,
            'EUR',
            (
                'Date, Transaction Details, Funds Out, Funds In'
            )
        )


CONFIG = [
    apply_hooks(MyBankImporter(account='Assets:MyBank:MyAccount'), [PredictPostings()])
]

Documentation

This section explains in detail the relevant concepts and artifacts needed for enhancing Beancount importers with machine learning.

Beancount Importers

Let's assume you have created an importer for "MyBank" called
``MyBankImporter``:

.. code:: python

    class MyBankImporter(importer.ImporterProtocol):
        """My existing importer"""
        # the actual importer logic would be here...

Note:
This documentation assumes you already know how to create Beancount importers.
Relevant documentation can be found in the `beancount import documentation
<https://beancount.github.io/docs/importing_external_data.html>`__.
With the functionality of beancount.ingest, users can
write their own importers and use them to convert downloaded bank statements
into lists of Beancount entries.
An example is provided as part of beancount v2's source code under
`examples/ingest/office
<https://github.com/beancount/beancount/tree/v2/examples/ingest/office>`__.

smart_importer only works by appending onto incomplete single-legged postings
(i.e. It will not work by modifying postings with accounts like "Expenses:TODO").
The `extract` method in the importer should follow the
`latest interface <https://github.com/beancount/beancount/blob/v2/beancount/ingest/importer.py#L61>`__
and include an `existing_entries` argument.

Applying `smart_importer` hooks

Any Beancount importer can be converted into a smart importer by applying one of the following hooks:

• PredictPostings - predict the list of postings.
• PredictPayees- predict the payee of the transaction.
• DuplicateDetector - detect duplicates

For example, to convert an existing MyBankImporter into a smart importer:

.. code:: python

from your_custom_importer import MyBankImporter
from smart_importer import apply_hooks, PredictPayees, PredictPostings

my_bank_importer =  MyBankImporter('whatever', 'config', 'is', 'needed')
apply_hooks(my_bank_importer, [PredictPostings(), PredictPayees()])

CONFIG = [
    my_bank_importer,
]

Note that the importer hooks need to be applied to an importer instance, as shown above.

Specifying Training Data

The ``smart_importer`` hooks need training data, i.e. an existing list of
transactions in order to be effective. Training data can be specified by
calling bean-extract with an argument that references existing Beancount
transactions, e.g., ``bean-extract -f existing_transactions.beancount``. When
using the importer in Fava, the existing entries are used as training data
automatically.


Usage with Fava
~~~~~~~~~~~~~~~

Smart importers play nice with `Fava <https://github.com/beancount/fava>`__.
This means you can use smart importers together with Fava in the exact same way
as you would do with a conventional importer. See `Fava's help on importers
<https://github.com/beancount/fava/blob/main/src/fava/help/import.md>`__ for more
information.


Development
-----------

Pull requests welcome!


Executing the Unit Tests

Simply run (requires tox):

.. code:: bash

make test

Configuring Logging

Python's `logging` module is used by the smart_importer module.
The according log level can be changed as follows:


.. code:: python

    import logging
    logging.getLogger('smart_importer').setLevel(logging.DEBUG)


Using Tokenizer
~~~~~~~~~~~~~~~~~~

Custom tokenizers can let smart_importer support more languages, eg. Chinese.

If you looking for Chinese tokenizer, you can follow this example:

First make sure that `jieba` is installed in your python environment:

.. code:: bash

    pip install jieba


In your importer code, you can then pass `jieba` to be used as tokenizer:

.. code:: python

    from smart_importer import PredictPostings
    import jieba

    jieba.initialize()
    tokenizer = lambda s: list(jieba.cut(s))

    predictor = PredictPostings(string_tokenizer=tokenizer)