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Cell functions in Python scripts (called through Basic)

 
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Villeroy
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PostPosted: Tue Jul 10, 2007 12:02 pm    Post subject: Cell functions in Python scripts (called through Basic) Reply with quote

Thanks to rvc44 who asked for an example how to use c.s.s.script.ArrayWrapper in thread http://www.oooforum.org/forum/viewtopic.phtml?t=59514. I was not aware of such a thing.
With regards to badzil, caresia, ms777, thom314 in thread
http://www.oooforum.org/forum/viewtopic.phtml?t=41162&highlight=omasterscriptprovider
This is a Basic module which can provide user defined functions. It passes over the job to a Python script.
Sheet functions which want to be usable as array functions, need to return a plain 2D-array rather than a list-of-lists array as used with get/setDataArray(ListOfList). Python can not handle multidimensional arrays. All the built-in types of arrays, which may be nested.
Without the c.s.s.script.ArrayWrapper the Python can not return a valid array.
First the Basic code, called by the sheet cell(s). Unfortunately we can not pass variable arrays like =PYFUNCTION("fncName";{arg1;arg2;...})
But this is reported to be changed in next stable version.
Code:

REM  *****  BASIC  *****
REM Keep a global reference to the ScriptProvider, since this stuff may be called many times:
Global g_MasterScriptProvider
REM Specify location of Python script, providing cell functions:
Const URL_Main = "vnd.sun.star.script:sheetFunction.py$"
Const URL_Args = "?language=Python&location=user"
Function getDoubleOf(data)
   sURL = URL_Main & "getDoubleOf" & URL_Args
   oMSP = getMasterScriptProvider()
   oScript = oMSP.getScript(sURL)
   x = oScript.invoke(Array(data),Array(),Array())
   getDoubleOf = x
end Function
Function getMasterScriptProvider()
   if NOT isObject(g_MasterScriptProvider) then
      oMasterScriptProviderFactory = createUnoService("com.sun.star.script.provider.MasterScriptProviderFactory")
      g_MasterScriptProvider = oMasterScriptProviderFactory.createScriptProvider("")
   endif
   getMasterScriptProvider = g_MasterScriptProvider
End Function

Now the Python function
Code:

import uno

def getDoubleOf(data):
    '''Simple demo-function duplicating plain cell values 1->2, "A"->"AA"
    Thanks to the c.s.s.script.ArrayWrapper it works in array context as well. To be called through a StarBasic wrapper.'''
    # cheap msgbox in scripting context:
    # raise Exception(repr(data))
    if hasattr(data[0], '__iter__'):
        # two lists:
        rows = []
        wrapper = uno.createUnoStruct('com.sun.star.script.ArrayWrapper')
        # =A1:B2 passes a one-based array to a Basic function. Let's assume the same here:
        # (Apparently it makes no difference if IsZeroIndex or not)
        wrapper.IsZeroIndex = False
        for row in data:
            column = []
            for val in row:
                try:
                    column.append(val * 2)
                except:
                    column.append(None)
            rows.append(tuple(column))
        # returning the mere list of list fails:
        # return tuple(rows)
        # here comes the wrapper into play:
        wrapper.Array = tuple(rows)
        return wrapper
   
    elif hasattr(data, '__abs__'):
        return data *2
    else:
        return None

Remark for non-Pythoniacs:
Contrary to an extensible type [list], a (tuple) is like a "frozen" array. The python bridge passes and handles tuples only. We convert lists to tuples by built-in function tuple(list)


This is the same stuff in Basic (without the side effect of doubling strings):
Code:

Function basGetDoubleOf(data)
if isArray(data) then
   iLB1 = lBound(data(),1)
   iUB1 = uBound(data(),1)
   iLB2 = lBound(data(),2)
   iUB2 = uBound(data(),2)
   Dim a(iLB1 to iUB1, iLB2 to iUB2)
   for i = iLB1 to iUB1
      for j = iLB2 to iUB2
         v = data(i, j)
         if isNumeric(v) then
         a(i, j) = v
       endif
      next j
   next i
   basGetDoubleOf = a()
elseif isNumeric(data) then
   basGetDoubleOf = data *2
else
   basGetDoubleOf = Null
endif

Both functions seem to have the same problem in array context. First they return Err:522 (circular reference), after a hard recalculation there remain two errors on top of the array until we change something in the source range.
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Villeroy
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Joined: 04 Oct 2004
Posts: 10106
Location: Germany

PostPosted: Fri Jan 30, 2009 6:46 am    Post subject: Reply with quote

Just a more useful example. There are reasons why no spreadsheet comes with a built-in soundex-function, but every database engine comes with some implementation of soundex. Even Base's integrated HSQLDB hasa one.
Anyway, people are addicted to spreadsheets and there is a smart and crispy soundex implementation found at http://code.activestate.com/recipes/52213/

Add this function to the above Basic module:
Code:

Function SOUNDEX(s$, optional iLen%)
   sURL = URL_Main & "soundex" & URL_Args
   oMSP = getMasterScriptProvider()
   oScript = oMSP.getScript(sURL)
   
   if isMissing(iLen) then
      i = 4
   else
      i = cInt(iLen)
   endif
   x = oScript.invoke(Array(s,i),Array(),Array())
   SOUNDEX = x
End Function

and the code from http://code.activestate.com/recipes/52213/ to Python-module "sheetFunction.py" in your <user-profile>/Scripts/python/
Hint: Writer can read and write plain text with Unix line-feeds (LF) using file type "Encoded Text (*.txt)". Paste the code snipped as unformatted text.
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