Weighting Schemes: Implementing Piv+ Normalization

[Vivek Pal]

> Two of those are compile errors, suggesting you aren't pulling in the
> right header file (it's in common/serialise-double.h I believe).

Thanks, fixed those errors.

> I can't tell for sure without seeing the diff. You may mean just
> `ptr++`? But it could be something else, depending on what you're
> trying to do.

I'm trying to unserialise normalization strings (e.g. "nfn", "nbsl"  etc.)
along with the new double parameters (s and delta) but
it isn't turning out to be smooth because there's no method for
unserialising strings in serialise-double.h

Although, doing just

const string normals = ptr++; or, const string normals = static_cast<const
string>ptr++; fixes compile errors.

But tfidfweight3 test case is failing with remote backends :-

$ ./runtest gdb ./apitest -v tfidfweight3

Running test: tfidfweight3... SerialisationError: REMOTE:Bad encoded
double: short mantissa (context: remote:prog(../bin/xapian-progsrv -t300000
.glass/db=apitest_simpledata)

I'm wondering if I need to introduce a new method in serialise-double.h for
string parameters (normalizations in this case)? To be honest, I have
little idea about that part of Xapian so probably a workaround might be
better. :)

Thanks,
Vivek



On Thu, Jul 28, 2016 at 3:14 AM, James Aylett <james-xapian at tartarus.org>
wrote:

> On Wed, Jul 27, 2016 at 11:38:58PM +0530, Vivek Pal wrote:
>
> > But I'm running into some issues with Piv+ normalization. In the Piv+
> > formula  , there are two parameters (s and delta) that control the weight
> > assigned. I think the way I'm serialising and unserialising these
> > parameters has some issues which is causing a few errors,
> > http://pastebin.com/yCyuvF1X.  Any suggestion is appreciated!
>
> Two of those are compile errors, suggesting you aren't pulling in the
> right header file (it's in common/serialise-double.h I believe).
>
> This one:
>
> ----------------------------------------------------------------------
> weight/tfidfweight.cc: In member function 'virtual
> Xapian::TfIdfWeight* Xapian::TfIdfWeight::unserialise(const string&)
> const':
>
> weight/tfidfweight.cc:87:37: error: conversion from 'const char' to
> non-scalar type 'const string {aka const
> std::__cxx11::basic_string<char>}' requested
>
>      const string normals = (*(ptr)++);
>                                      ^
> ----------------------------------------------------------------------
>
> I can't tell for sure without seeing the diff. You may mean just
> `ptr++`? But it could be something else, depending on what you're
> trying to do.
>
> > Also, I was wondering if we want to have pivoted normalization weighting
> as
> > a separate weighting scheme in Xapian as it will make a way to add
> support
> > of different variations of pivoted normalization in the future?
>
> This is more of a question for Olly, who I believe should be back on
> reliable internet later this week.
>
> J
>
> --
>   James Aylett, occasional trouble-maker
>   xapian.org
>
>
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