jpcorpreg 2.0.1

jpcorpreg is a Python library that downloads corporate registry which is published in the Corporate Number Publication Site as a data frame.

jpcorpreg

jpcorpreg is a Python library that downloads corporate registry which is published in the Corporate Number Publication Site as a data frame.

Installation

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jpcorpreg is available on pip installation.

$ python -m pip install jpcorpreg

GitHub Install

Installing the latest version from GitHub:

$ git clone https://github.com/new-village/jpcorpreg
$ cd jpcorpreg
$ pip install -e .

Usage

This section demonstrates how to use this library to load and process data from the National Tax Agency's Corporate Number Publication Site.

Starting with version 2.0.0, jpcorpreg provides a robust object-oriented client (CorporateRegistryClient) optimized for reading large datasets and native Parquet partitioning.

Initializing the Client

First, import and initialize the client:

from jpcorpreg import CorporateRegistryClient
client = CorporateRegistryClient()

Direct Data Loading

To download data for a specific prefecture as a pandas DataFrame, use the fetch method. By passing the prefecture name in as an argument, it will perform streaming fetch from the National Tax site:

>>> df = client.fetch("Shimane")

To execute the download across all prefectures across Japan, simply leave the parameter empty or pass "All":

>>> df = client.fetch()

Differential Data Loading

If you want to download only the daily differential updates (sabun), use the fetch_diff function. By passing a date in YYYYMMDD format, you can download the diff for that specific date. If no date is provided, the latest available diff is returned.

>>> df = client.fetch_diff("20260220")

Parquet Output and Partitioning

If you prefer to save the downloaded data for data lakes explicitly, pass format="parquet". You can also supply the partition_cols argument so that the dataset is written in partitioned directories on disk. The function returns the output base directory path.

Partitioning Context Notes:

• For fetch() (full wash dataset), use something like partition_cols=["prefecture_name"]. Avoid using "update_date" on a full data wash to prevent query fragmentation.
• For fetch_diff() (daily diff data), use partition_cols=["update_date"] to append daily updates seamlessly into your data lake structure.

>>> # Example: Output differential data partitioned by update_date
>>> out_dir = client.fetch_diff(format="parquet", partition_cols=["update_date"])

You can then read the dynamically generated Parquet Dataset efficiently with pandas or PyArrow:

>>> import pandas as pd
>>> df = pd.read_parquet(out_dir)