Re: Binary syntax reduction [Was: Lengthy discussion...]

[Daniel J S. <dan...@ie...>]

Daniel J Sebald wrote:

> binary {3 | xy | xyz | xyzc} {format="string"} {endian=little}


Or perhaps a better way of doing this would be

binary {#} {columns} {format="string"} {endian=big}

Here

binary #  :  Matrix format, # specifies the number of components per 
matrix element.

binary # columns  :  Binary data has # columns of "string" data format.

How's that?  No user functions, no strings, but I think that would cover 
most applications that use temporary data as opposed to, say, archived 
ascii where strings etc. are useful.

I could implement that as df_readbinary() fairly easily.  That would 
allow binary data for 2D data.


So, how about 3D data?  It already exists.  But let's examine its 
structure.  Basically, inside plot3d.c is the following:

    if (df_matrix)
        xdatum = df_3dmatrix(this_plot, NEED_PALETTE(this_plot));
    else {
<snip>
        while ((j = df_readline(v,MAXDATACOLS)) != DF_EOF) {

Inside of df_3dmatrix is some code that looks very similar similar to 
df_readline (with using specs, etc.... maybe "using" can't be discarded 
afterall) , but instead df_3dmatrix does the work of storing the data in 
the plot structure, rather than passing data back to plot3d.c for 
interpretting.

The question I pose is could df_3dmatrix be replaced by df_readline() 
which uses df_readbinary internally?  The advantage of df_3dmatrix() is 
that it has a short little loop to do the storage rather than passing 
back a v[] vector.  However, it isn't consistent with the most 
predominant gnuplot "paradigm" for interpretting and storing data. 
 Plus, if there is a df_readline() which is very similar to df_3dmatrix, 
it is a bit of code repetition.

Now, I know Ethan would like to pass in the plot structure pointer to 
the reading routine.  Perhaps then the idea is to move away from that 
strategy, and df_3dmatrix is more the desired model.

Here are some interesting comments from the code and online help:

/* FIXME HBB 20001207: doesn't respect 'index' at all, even though it
 * could, and probably should. */
static float **
df_read_matrix(int *rows, int *cols)

 The `index` keyword is not supported, since the file format allows only one
 surface per file.  The `every` and `using` filters are supported.  `using`
 operates as if the data were read in the above triplet form.

So, it seems maybe its desirable to have 'using' as part of the binary 
command.  But, I don't think 'index' works from what is in a 
gnuplot-binary file.  There is only the value <N+1> at the start of the 
file, not the other dimension.  So there is no way of knowing when to 
end one record without something  like "record=120x150".  But, I'm 
drifting to the geezer camp, not allowing more than one record per file.

Dan