Reading digital XBRL/iXBRL account documents - for sharing
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What's this?

The goal of the project in general is to be able to extract accounts data from any company balance sheet from Companies House including those submitted as an image/scan only.

This repository exists so that others can join in on making this data accessible.

Ultimately we want to be able to retrive the variables needed to fill out the summary equation:

Assets = Liabilities + Shareholders' Equity

Parsing digital company accounts data

The module is for extracting data from xbrl company account documents, both XBRLi and older XBRL formats. It's currently under development so it might be wise to play with it a bit and check you're getting back what you expected!

The folder example_data_XBRL_iXBRL contains an assortment of recent companies house accounts electronic records to play with as examples.

extract_XBRL.ipynb hosts example usage of the module in extracting accounts.

The file example_extracted_XBRL_data.csv contains the results of applying these methods to all of the example digital accounts files, flattened by a helper function into an SQL-friendly format.

The software, before "flattening", returns a python dict object:

	{doc_name: <original file name>,
	doc_type: <file ending, html or xml>,
	doc_upload_date: <date of upload>,
	arc_name: <name of archive file from CH it was sourced from>,
	doc_parsed: <records True if the document was successfully parsed by BeautifulSoup>,
	doc_balancesheetdate: <date as extracted from filename>,
	doc_companieshouseregisterednumber: <CH company number as extracted from filename>
	doc_standard_type: <if found, name of accounting standard used in doc>,
	doc_standard_date: <if found, date of issue of the accounting standard used>,
	doc_standard_link: <if found, web link to official schema of the discovered accounting standard>,
	elements: [{name: <name found beginning with ix>,
				value: <result of get_text() applied to element, parsed to numeric if unit exists>,
				unit: <from unitref attribute, will follow reference and recognise USD, GBP and EUR>,
				date: <from contextref attribute, will follow reference>}

Parsing imaged company accounts data.

Experimenting with reading tables from CH PDF records. Note, you can't do much without Tesseract OCR version 4 (currently alpha) installed, and all of the system commands that call external software in these notebooks are set up for a linux machine.

The example PDF's, drawn randomly from Companies House a while back, are in example_data_PDF directory.

02_process_pdfs_to_data.ipynb uses Tesseract to "read" a pdf and convert it to a table of words with locations and confidences in the translation.
There's a lot in that notebook that pre-processes images and fixes some quirks with how the PDF's are encoded.

03_Extract_PDF_data gathers variables from the balance sheet entries in the PDF by first narrowing to the pages likely to BE the balance sheet, then using a sophisticated regex (from to get lines formatted with (simplified). I'm now working on reliably extracting the reporting unit from the PDF by searching for the most common element starting with £, $, EUR, and whatever number of zeros after it.

I'm assuming the dates of the records can be determined from metadata on the Companies House API, but haven't actually checked...

To be fixed;

"parsed" field should be False if no elements extracted from document. Currently it's False only if the document can't be opened in the first place.

On switching to more elegant method of iterating through elements regardless of doc format, number of records with less than 5 numerical elements increased from 0.5 to 1 percent. May be artefact of ingesting full years data but should be checked in case bug introduced.

(For reference; num of records with few numerical entries has proven to be a good way of eyeballing data quality - there's too many edge cases in terms of content and formats so there's no definitive sign when things start to partially fail...)