Re: multiple plot lines with plot '-'

[<pl...@pi...>]

On 05/19/12 00:19, Tait wrote:
>> If you are suggesting that associating a file descriptor with a file;
>> opening; reading; closing; reopening (with implies a seek(0) ) ; and
>> rereading   is the same as opening ; reading up to 'e' marker *in the
>> data* then continuing to read the same opened device,  I have to say
>> your reasoning is getting a bit contrived.
>>
>> I find it hard to see that as being the same behavior.
>
> Maybe we're drifting beyond the point of useful distinction. I mean in
> terms of behavior the users see, plot consumes inputs. Each data set
> given to plot is consumed by that plot. Plot 'file' opens and reads
> file; it's consumed in generating the plot, and everything is reset
> for the next plot, whether in the same plot command or in a
> subsequent. For instance...
> 	plot 'file1'
> 	plot 'file2'
> is the same -- for purposes of reading input -- as
> 	plot 'file1', 'file2'
>
> And...
> 	plot '-'
> 	...
> 	e
> 	plot '-'
> 	...
> 	e
> is the same, in terms of reading input, as
> 	plot '-', '-'
> 	...
> 	e
> 	...
> 	e
>
> In both cases, the data is consumed by the plot command, and the
> next plot command begins consuming a new set of data (even though
> file1 and file2 may be the same, and thus consume the same data
> multiple times).

A test of whether the behaviour is the same would be to use a variable 
to define the data source:

datasrc='file1.dat'
plot datasrc, datasrc


datasrc='-'
plot datasrc, datasrc

It would be nice if gnuplot was data source agnostic in that way, but I 
can see why it was thought to be more useful to treat '-' as a special case.

That's the way it was done and there is not sufficient problems to 
suggest breaking compatibility.


regards. Peter.



>
> That's what I mean when I say the behavior of '-' and 'file'
> are the same. I think I see the model you suggest, though,
> which is more like saying the lines between plot and e create
> a named record called '-', which would then be treated the same
> as a named record called 'file1' and referenced multiple times.
> If those lines could be given a name explicitly -- other than
> '-' -- and could exist outside of an appendage to a plot
> command, then I think that model would make more sense. And
> that's a little closer to what Allin was suggesting, which is
> why I liked that idea.
>
>