Time formats [was Re: Feature request - assignment in expressions]

[Ethan M. <merritt@u.washington.edu>]

On Tuesday 08 May 2007 09:43, Juergen Wieferink wrote:
> 
> > I have never understood the time-handling code.  I suspect that the
> > whole special case time format mechanism is no longer needed, as the same
> > goal can be achieved using general string-handling functions.
> > In your case, you probably need to use some combination of stringcolumn()
> > strptime() strftime() rather than setting a time format.
> 
> I don't think so.  I see two problems (probably there are more):
> * Automatic tic generation is date/time aware.  This could be
>   adjusted manually, but the automatic tics wouldn't be too sensible.

Could be.  As I said, I am not familiar with the time format options.

> * Tic label generation.  The command "set format" just takes a
>   format string, which is used either for date/time or ordinary
>   numbers.  The functions strptime() and strftime() only work with a
>   more flexible "set format" which takes a string valued expression, which
>   is evaluated at plot time.

Sure.  But that could be a useful addition in its own right.
I didn't mean to say that the time format options could be deprecated
with no additional work; I just meant that the basic pieces are in place
to replace them with a more general mechanism.

Don't forget that we have several long-standing requests to extend
the time format system so that it can handle intervals smaller than
a second, and also to allow it to handle spherical coordinate systems
deg/min/sec/fractional-sec

One could write a lot of special-purpose code to handle these
extensions, but I would rather see the effort spent on implementing
a generic mechanism of which the existing time formats and the 
proposed geographic variants are just user-configurable examples.


-- 
Ethan A Merritt            Courier Deliveries: 1959 NE Pacific
Dept of Biochemistry
Health Sciences Building
University of Washington - Seattle WA 98195-7742