Formulas implements an interpreter for excel formulas, which parses and compile excel formulas expressions.

Moreover, it compiles excel workbooks to python and executes without using the Excel COM server. Hence, Excel is not needed.

To install it use (with root privileges):

$ pip install formulas

Or download the last git version and use (with root privileges):

$ python setup.py install

Some additional functionality is enabled installing the following extras:

• excel: enables to compile excel workbooks to python and execute using: :class:`~formulas.excel.ExcelModel`.
• plot: enables to plot the formula ast and the excel model.

To install formulas and all extras, do:

$ pip install formulas[all]

An example how to parse and execute an excel formula is the following:

>>> import formulas
>>> func = formulas.Parser().ast('=(1 + 1) + B3 / A2')[1].compile()

To visualize formula model and get the input order you can do the following:

.. dispatcher:: func
   :opt: graph_attr={'ratio': '1'}
   :code:

    >>> list(func.inputs)
    ['A2', 'B3']
    >>> func.plot(view=False)  # Set view=True to plot in the default browser.
    SiteMap([(=((1 + 1) + (B3 / A2)), SiteMap())])

Finally to execute the formula and plot the workflow:

.. dispatcher:: func
   :opt: workflow=True, graph_attr={'ratio': '1'}
   :code:

    >>> func(1, 5)
    OperatorArray(7.0, dtype=object)
    >>> func.plot(workflow=True, view=False)  # Set view=True to plot in the default browser.
    SiteMap([(=((1 + 1) + (B3 / A2)), SiteMap())])

An example how to load, calculate, and write an excel workbook is the following:

.. testsetup::

    >>> import os.path as osp
    >>> from setup import mydir
    >>> fpath = osp.join(mydir, 'test/test_files/excel.xlsx')

>>> import formulas
>>> fpath = 'file.xlsx'  # doctest: +SKIP
>>> xl_model = formulas.ExcelModel().loads(fpath).finish()
>>> xl_model.calculate()
Solution(...)
>>> xl_model.write()
{'EXCEL.XLSX': {Book: <openpyxl.workbook.workbook.Workbook ...>}}

To compile and execute a sub model from a workbook you can do the following:

>>> inputs = ["'[EXCEL.XLSX]DATA'!A2"]  # input cells
>>> outputs = ["'[EXCEL.XLSX]DATA'!C2"]  # output cells
>>> func = xl_model.compile(inputs, outputs)
>>> func(2).value[0,0]
4.0

.. dispatcher:: func
   :code:

    >>> func.plot(view=False)  # Set view=True to plot in the default browser.
    SiteMap([(Dispatcher ..., SiteMap())])

An example how to add a custom function to the formula parser is the following:

>>> import formulas
>>> FUNCTIONS = formulas.get_functions()
>>> FUNCTIONS['MYFUNC'] = lambda x, y: 1 + y + x
>>> func = formulas.Parser().ast('=MYFUNC(1, 2)')[1].compile()
>>> func()
4

Things yet to do implement the missing excel formulas.