Re: [Help-gsl] Reading vectors and matrices from text files

[Tommy Nordgren]

I think that in general, the best way to read data is to use a  
parser, generated by
a parser generator (for example bison or antlr).

the following grammar will read a single vector of integers:

vector : vectorbegin intlist '\n' { YYACCEPT; }
        ;
vectorbegin :  {vector_buffer.clear(); }
        ;
intlist:   INTEGER     { vector_buffer.push_back($1); }
        |    intlist ',' INTEGER {vector_buffer.push_back($3); }
        ;

	Here I've assumed that vector_buffer is a global std::vector<int>,  
which will contain
the vector read when the parser returns.
Doubles can be handled in a similar way.

Dec 26, 2005 kl. 7:11 AM skrev Ivan Adzhubey:

> Hi,
>
> What is the best way to read vector/matrix data from a file? The
> gsl_*_fscanf() family og functions surprisingly lack the format  
> specification
> parameter and nothing in the documentation hints on how they really  
> work. I
> have pre-generated sets of vectors stored in text files in the  
> following
> simple format:
>
> 1,2,3,4,5,10
> 2,2,4,5,6,20
> ...
>
> i.e., one vector per line, comma-separated vector elements. The  
> idea is to
> read the whole block of data in and then loop over it (creating vector
> views?) doing calculations.
>
> Next step would be to replace text files as an input source with  
> the database,
> Postgresql in my case, since I need to process very large data  
> sets, e.g.
> ranging from 100,000 to 100,000,000 of sample vectors. I appreciate  
> if anyone
> with the similar experience would share it.
>
> TIA,
> Ivan
>
>
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"Home is not where you are born, but where your heart finds peace" -
Tommy Nordgren, "The dying old crone"