Re: [Gnuplot-info] strptime() fails to recognize negative hours

[Sergei N. <vo...@ra...>]

В письме от четверг, 2 апреля 2020 г. 19:34:50 MSK пользователь Hans-Bernhard 
Bröker написал:

> So the sign of the hours field extends over to the minutes and seconds.
> 
> I'll assume (although the documentation doesn't say so) that this was
> meant to work like that.
> 
> > gnuplot> print strptime(myTimeFmt,"-01:-02:03.4")
> > -3723.4
> > gnuplot> print strptime(myTimeFmt,"-01:+02:03.4")
> > -3723.4
> 
> Hmm, so there's no way to flip the minutes back to positive once the
> hours are negative.  That IMHO casts doubt on the whole idea of
> inheriting the sign from one field to the other (not to mention what
> might happen if some devious mind decided to use these fields in reverse
> order, i.e. "%tS:%tM:%tH").

Well, this whole mess comes from the fact that gnuplot, it seems, can not read 
A COLUMN in an arbitrary formatted way. 

There is a substitute for time, i.e. 'timefmt' where this thing with a sign is 
probably a bug and has to be fixed in such a way that it is taken into account 
when it sits only before the %tH. Otherwise, it has no meaning.

But it would be cool to make a formatted reading available:

set xdata format "%tH:%tM:%tS"
set ydata format "%tH:%tM:%tS"
plot 'datafile' using ($1.1+$1.2/60+$1.3/3600):($2.1+$2.2/60+$2.3/3600)

where dotted notation indicates a positional value according to a format 
string.

Thanks,
Sergei