.. _r2pythonrst:

==============================
Convert a R script into Python
==============================


.. only:: html

    **Links:** :download:`notebook <r2python.ipynb>`, :downloadlink:`html <r2python2html.html>`, :download:`PDF <r2python.pdf>`, :download:`python <r2python.py>`, :downloadlink:`slides <r2python.slides.html>`, :githublink:`GitHub|_doc/notebooks/r2python.ipynb|*`


This notebook introduces the function
`r2python <http://www.xavierdupre.fr/app/pyensae/helpsphinx/pyensae/languages/rconverter.html>`__ which converts *R* into *Python*. It
does not work for eveything, it is being improved everytime it is
needed. This notebook was executed with the following versions:

.. code:: ipython3

    import sys
    print(sys.version)


.. parsed-literal::
    3.10.5 (tags/v3.10.5:f377153, Jun  6 2022, 16:14:13) [MSC v.1929 64 bit (AMD64)]


.. code:: ipython3

    text = !python -m pip freeze antlr4-python3-runtime

.. code:: ipython3

    [t for t in text if "antlr" in t]




.. parsed-literal::
    ['antlr4-python3-runtime==4.10']



A script as an example:

.. code:: ipython3

    rscript = """
    nb=function(y=1930){
    debut=1816
    MatDFemale=matrix(D$Female,nrow=111)
    colnames(MatDFemale)=(debut+0):198
    cly=(y-debut+1):111
    deces=diag(MatDFemale[:,cly[cly%in%1:199]])
    return(c(B$Female[B$Year==y],deces))}
    """

.. code:: ipython3

    from pyensae.languages.rconverter import r2python
    print(r2python(rscript, pep8=True))


.. parsed-literal::
    from python2r_helper import make_tuple
    
    def nb(y=1930):
        debut = 1816
        MatDFemale = matrix(D . Female, nrow=111)
        colnames(MatDFemale) .set(range((debut + 0), 198))
        cly = range((y - debut + 1), 111)
        deces = diag(MatDFemale[:, cly[set(cly) & set(range(1, 199))]])
        return make_tuple(B . Female[B . Year == y], deces)
    


It adds some not implemented function such as
``colnames(MatDFemale) .set(range((debut + 0), 198))`` because the
original syntax ``colnames(MatDFemale)=debut+0:198`` does not work in
*Python*. The conversion does not fix indices (first position is zero in
*Python* and 1 in *R*). The bracket ``(debut+0):198`` are needed to tell
the converter the beginning of the expression. The operator ``%in%`` is
converted into a set intersection.

The unit tests check the function is working on the following list of
example
`unittests/ut_languages/data <https://github.com/sdpython/pyensae/tree/master/_unittests/ut_languages/data>`__.
Anything not included in that list might require a few code change. Some
instructions ``colnames(MatDFemale) .set(range((debut + 0), 198))``
should probably be rewritten.

.. code:: ipython3

    import numpy
    
    def matrix(array, nrow=None):
        arr = numpy.array(array)
        if nrow is not None:
            ncol = len(arr) // nrow
            arr = numpy.resize(arr, new_shape=(nrow, ncol))
        return arr
    
    def colnames(df):
        if isinstance(df, pandas.DataFrame):
            return list(df.columns)
        raise TypeError(type(df))
            
    def make_tuple(*el, aslist=True):
        if aslist:
            return list(el)
        return tuple(el)