[GRASSLIST:435] Re: m.in.e00 question

[Michael Ash]

Could I ask for a bit more clarification on this matter?  I
have had some difficulty with .e00 files and the associated
dig_cats/ files that are created.

When I have chosen the "-i" option of m.in.e00 and then
copied the resulting dig/, dig_att/, and dig_plus/ files to
correspond to the various dig_cats/ files, I have mismatches
between areas on the map and the associated dig_cats labels.
The problem does not occur when I omit the "-i" option of
m.in.e00.  So my conclusion had been to omit the "-i"
option.

However, Michel's post suggests that "-i" is the appropriate
option because coverage-# can be shuffled by subsequent
processing while coverage-ID is fixed.  I would be grateful
for clarification.

Best regards,

Michael


> Keith J. Forbes wrote:
> > FLAG: Set the following flag?
> >     Link attributes by coverage-ID not by coverage-#?
> > Question: What exactly does this option mean?
>
> Each feature in e00 file (and in Arc/Info) have an internal
> identifier (name_of_layer-#) to link attributes and geometry.
> It is however a bad practice to use this number as an external
> link because the internal numbering may change if you do
> some operation (cleaning after erasing some objects, etc.).
> # is computed automaticaly and you cannot modify it.
> There is another identifier (name_of-layer-ID) that is
> entirely controled by the user, and can therefore be used
> to link your coverage to an external database, etc...
>
> In practice for m.in.e00 :
> - the is one attribute entry per graphic object (line, area, point)
> so you should use the normal behaviour of the program.
> - in some case, you want to consider all objects having the
> same ID as one object in Grass, or the # links are broken
> (yes, sometimes you can get really bad datasets !), so you
> may want to try the ID number.
>
> Honestly, its also an historical feature : the first release
> used (incorrectly) ID for the link...