How do xlrd, xlwt, xlutils work with Excel in the low level?

Question

They are all open source Python packages to control Excel (see python-excel ). I am still trying to understand their code. If anyone could give a hint, do how they connect in a low lever to Excel? Via xml, Excel API, or some other basic Python packages?

Answer 1

If we are talking about reading and writing XLS files, basically xlrd and xlwt follow the OpenOffice.org document/specification describing Excel's format and BIFF (Binary Interchange File Format) records to read and write XLS files. If you would inspect the xlwt source code , you would find it manipulates the BIFF records for everything needs to be written: creating workbook, worksheets, writing data, formatting, alignment etc.

With XLSX the story is a bit different. To read XLSX xlrd relies on the openxmlformats XML schemas and use built into Python ElementTree XML parsers ( cElementTree if available, otherwise ElementTree ) to parse the XLSX file which is, to simplify, a zip archive containing XML files inside. Here is a good overview of what is inside the archive:

• Anatomy of OOXML - xlsx

I would also recommend studying the xlsxwriter module - from my point of view, the package is much better documented and the code is much more cleaner and readable than xlwt or xlrd .