Re: question about binary plot data

[Chris K <gnu...@li...>]

Daniel J Sebald wrote:
> Daniel J Sebald wrote:
>>> plot "-" binary record=5x2 using 1:2 with linespoints,\
>>>      "-" binary record=5x2 using 1:2 with linespoints
>>>
>>> cat "command-2.gp" "binary.dat" "binary.dat" | gnuplot
>>>
>>> The error message seems to indicated the second "-" is the problem:
>>>
>>> gnuplot> plot "-" binary record=5x2 using 1:($2) with
>>> linespoints,     "-"
>>> binary record=5x2 using 1:($2)**2 with linespoints
>>>
>>>                                   ^
>>>          line 0: warning: Skipping data file with no valid points
>>>
> 
> ... I wonder why the above is failing.  The warning makes me think that
> gnuplot believes it has run out of data.  Might you have an extra CR or
> LF as a result of the cat process?
> 
> Actually, this seems to work for me.  For example, try the attached
> files with the command
> 
> cat "command" "bin1.bin" "bin2.bin" | gnuplot
> 
> and you should see a PNG file appear in the directory.

Your example worked.  So I have written more test cases, and I have isolated the
trigger for failure.

This works:

set title "test-2.gp"
plot "-" binary record=10 using 0:1 with linespoints,\
     "-" binary record=10 using 0:($1)**2 with linespoints

This works:

set title "test-3.gp"
plot "-" binary record=10 using 0:1 with linespoints,\
     "-" binary record=5x2 using 1:($2)**2 with linespoints

This fails, saying "line 0: warning: Skipping data file with no valid points"

set title "test-4.gp"
plot "-" binary record=5x2 using 1:2 with linespoints,\
     "-" binary record=5x2 using 1:($2)**2 with linespoints

The use of 5x2 instead of 10 in the first plot triggers the error.  I am going
to hypothesize that the first use of "record=5x2" causes it to read an amount of
data greater than "record=10".  But I have not read the code to check.

I see in datafile.c :

/* Daniel Sebald: added general binary 2d data support. (20 August 2004)
 */

So thanks for the help with this.

-- 
Chris