[GRASSLIST:8019] Re: dead lines?

[Radim Blazek]

On 8/22/05, M S <mseibel at gmail.com> wrote:
> so is there a way to "restore/ressurect" those lines that are dead?
> if they are deleted can you have the software restore them if u made a
> mistake when deleting them?

In theory eyes but it is not implemented in GRASS. 
Also line type is lost because type is set to 0 for dead lines.
If you change in read_nat.c rows

         if (itype == 0)   /* is it DEAD? */
        continue;

to
 
         if (itype == 0)   /* is it DEAD? */
             itype = GV_LINE;

it should change dead elements to lines.

In future it would be nice to reuse the space, there is already
struct recycle *recycle; for list of deleted lines in vector header
but it is not implemented.

Radim
 
 
> thanks
> 
> On 8/22/05, Radim Blazek <radim.blazek at gmail.com> wrote:
> > On 8/18/05, M S <mseibel at gmail.com> wrote:
> > > I read that v.clean "removes dead lines from your map.  Dead lines are
> > > vectors that have been marked for deleted in v.digit."
> > >
> > > I'm confused about these dead lines.  In v.digit (using grass 6.0) i
> > > delete lines and they go away, and then i get prompted to remove the
> > > associated record from the database.
> > >
> > > Are these lines really deleted at this point?
> > >
> > > It sounds like they are not removed until v.clean is run.  if this is
> > > the case, can these lines be restored PRIOR to running v.clean?
> > >
> > > Can someone rephrase  what v.clean does and what "dead lines" are?
> > >
> > > thanks!
> >
> >
> > If you delete a line in v.digit, it is only marked in the file as 'dead' but
> > it remains there and occupies space. If you run any module which
> > realy reads and writes lines (not g.copy) it writes only lines which
> > are 'alive'.
> > Usually you don't need to think about dead lines.
> >
> > Radim
> >
>