formulas 0.4.0

Install extras

Some additional functionality is enabled installing the following extras:

• excel: enables to compile Excel workbooks to python and execute

  using: ExcelModel.

• plot: enables to plot the formula ast and the Excel model.

To install formulas and all extras, do:

$ pip install formulas[all]

Parsing formula

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:

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

[graph]

Finally to execute the formula and plot the workflow:

>>> func(1, 5)
Array(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())])

[graph]

Excel workbook

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

>>> import formulas
>>> fpath, dir_output = 'excel.xlsx', 'output'
>>> xl_model = formulas.ExcelModel().loads(fpath).finish()
>>> xl_model.calculate()
Solution(...)
>>> xl_model.write(dirpath=dir_output)
{'EXCEL.XLSX': {Book: <openpyxl.workbook.workbook.Workbook ...>}}

Tip: If you have or could have circular references, add

circular=True to finish method.

To plot the dependency graph that depict relationships between Excel cells:

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

[graph]

To overwrite the default inputs that are defined by the excel file or to impose some value to a specific cell:

>>> xl_model.calculate(
...     inputs={
...         "'[EXCEL.XLSX]DATA'!A2": 3,  # To overwrite the default value.
...         "'[EXCEL.XLSX]DATA'!B3": 1  # To impose a value to B3 cell.
...     },
...     outputs=[
...        "'[EXCEL.XLSX]DATA'!C2", "'[EXCEL.XLSX]DATA'!C4"
...     ] # To define the outputs that you want to calculate.
... )
Solution([("'[EXCEL.XLSX]DATA'!A2", <Ranges>('[EXCEL.XLSX]DATA'!A2)=[[3]]),
          ("'[EXCEL.XLSX]DATA'!A3", <Ranges>('[EXCEL.XLSX]DATA'!A3)=[[6]]),
          ("'[EXCEL.XLSX]DATA'!B3", <Ranges>('[EXCEL.XLSX]DATA'!B3)=[[1]]),
          ("'[EXCEL.XLSX]DATA'!B2", <Ranges>('[EXCEL.XLSX]DATA'!B2)=[[9.0]]),
          ("'[EXCEL.XLSX]DATA'!C2", <Ranges>('[EXCEL.XLSX]DATA'!C2)=[[9.0]]),
          ("'[EXCEL.XLSX]DATA'!C4", <Ranges>('[EXCEL.XLSX]DATA'!C4)=[[1.0]])])

To build a single function out of an excel model with fixed inputs and outputs, you can use the compile method of the ExcelModel that returns a DispatchPipe. This is a function where the inputs and outputs are defined by the data node ids (i.e., cell references).

>>> func = xl_model.compile(
...     inputs=[
...         "'[EXCEL.XLSX]DATA'!A2",  # First argument of the function.
...         "'[EXCEL.XLSX]DATA'!B3"   # Second argument of the function.
...     ], # To define function inputs.
...     outputs=[
...         "'[EXCEL.XLSX]DATA'!C2", "'[EXCEL.XLSX]DATA'!C4"
...     ] # To define function outputs.
... )
>>> func
<schedula.utils.dsp.DispatchPipe object at ...>
>>> [v.value[0, 0] for v in func(3, 1)]  # To retrieve the data.
[9.0, 1.0]
>>> func.plot(view=False)  # Set view=True to plot in the default browser.
SiteMap([(ExcelModel, SiteMap())])

[graph]

Custom functions

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