formulas
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.
Basic Examples
The following sections will show how to:
- parse a Excel formulas;
- load, compile, and execute a Excel workbook;
- extract a sub-model from a Excel workbook;
- add a custom function.
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())])
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())])
Excel workbook
An example how to load, calculate, and write an Excel workbook is the following:
>>> import os.path as osp
>>> from setup import mydir
>>> fpath = osp.join(mydir, 'test/test_files/excel.xlsx')
>>> dir_output = osp.join(mydir, 'test/test_files/tmp')
>>> import formulas
>>> fpath, dir_output = 'excel.xlsx', 'output' # doctest: +SKIP
>>> xl_model = formulas.ExcelModel().loads(fpath).finish()
>>> xl_model.calculate()
Solution(...)
>>> xl_model.write(dirpath=dir_output)
{'EXCEL.XLSX': {Book: <openpyxl.workbook.workbook.Workbook ...>}}
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(...))])
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'!D2", <Ranges>('[EXCEL.XLSX]DATA'!D2)=[[1]]),
("'[EXCEL.XLSX]DATA'!B2", <Ranges>('[EXCEL.XLSX]DATA'!B2)=[[9.0]]),
("'[EXCEL.XLSX]DATA'!D3", <Ranges>('[EXCEL.XLSX]DATA'!D3)=[[2.0]]),
("'[EXCEL.XLSX]DATA'!C2", <Ranges>('[EXCEL.XLSX]DATA'!C2)=[[10.0]]),
("'[EXCEL.XLSX]DATA'!D4", <Ranges>('[EXCEL.XLSX]DATA'!D4)=[[3.0]]),
("'[EXCEL.XLSX]DATA'!C4", <Ranges>('[EXCEL.XLSX]DATA'!C4)=[[4.0]])])
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.
[10.0, 4.0]
>>> func.plot(view=False) # Set view=True to plot in the default browser.
SiteMap([(ExcelModel, SiteMap(...))])
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
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- License: EUPL-1.1
- Author: Vincenzo Arcidiacono
- Last update: N/A