Re: Minor knit pick: errors

[Ethan A M. <sf...@us...>]

On Wednesday, 17 September, 2014 11:33:40 pl...@pi... wrote:
> Hi,
> 
> it is not very helpful that gnuplot  does not distinguish between 
> non-existent files and files it cannot parse for plotting.
> 
>   warning: Skipping unreadable file ......
> 
> Whenever I get this I have to try to work out whether there is a typo or 
> come other error in the path specifier or whether there are some header 
> lines or other formatting problems with data in a file  that it is able 
> to find.

Could you be more specific?
I get several different errors.  It is true that "unreadable" can be misleading
for a file that doesn't exist at all, but in the case of formatting problems
in the file "Bad data on line X" seems clear enough.

gnuplot> plot 'notthere.dat'
         warning: Skipping unreadable file "notthere.dat"
         No data in plot

gnuplot> plot 'readprotected.dat'
         warning: Skipping unreadable file "readprotected.dat"
         No data in plot

gnuplot> plot 'emptyfile.dat'
         warning: Skipping data file with no valid points
                             ^
         x range is invalid

gnuplot> plot '/bin/true'
              ^
         Bad data on line 1 of file /bin/true


> since these must be quite different error conditions as far as where and 
> how they are trapped in the code, some distinction would be very helpful 
> in saving time finding the problem.
> 
> 
> Regards, Peter.