[Qgis-user] After deleting points, attribute rows persist
Bernhard Ströbl
bernhard.stroebl at jena.de
Tue Jan 8 01:16:45 PST 2019
Hi Matthias
Am 08.01.2019 um 09:21 schrieb Matthias Kuhn:
> On point layers, I was always thinking of points being composed of a
> single node. On multi point layers, I was thinking of each part being
> composed of a single node, so I wasn't thinking of "either a node or a
> point" but both. With this concept in mind, the whole set of available
> tools works fine and predictable for me.
Well, in GIS a vertex is normally defined as a point being part of a
line [1], [2] therefore calling a tool "vertex tool" and making it
working on points seems inconsistent to me (in the previous mail I
called it "node tool", that was my mistake, I know saw it is in fact
called "vertex tool"), although, as I said, I do not really care, just
pointing out.
>
> Moving parts is supported now via the node tool by selecting all nodes
> of a part. It's also possible to delete a part on a
> multiline/multipolygon layer with the node tool. So also with respect to
> this it doesn't do anything special for point layers.
Oh, I was not aware of this, although selecting only the nodes of one
part can be impossible with the new vertex tool (see my related mail
last month), so the use is limited.
>
> I can see, that it may lead to confusion sometimes as described in the
> original email here. I am not able to say how often this happens in
> comparison to how often the node tool is used consciously.
The delete part tool can lead to confusion, too. I regularly have users
that click delete part instead of delete feature and end up with
geometryless datasets. Concerning the original question I think the
behaviour to not delete the feature is definitely ok.
>
> The node tool even gives a hint on the message bar, that "the geometry
> has been cleared, please use the add part tool to set the geometry for
> this feature". So it's trying to not be too obscure. Maybe the whole
> confusion can be ironed out by polishing this text a bit?
>
> Considering the separate tool for moving parts of multi-geometries, I
> agree it sounds like a valid tool to have, but I am a bit concerned of
> the clutter to benefit ratio. Does anyone have an idea how often this
> would be useful in reality?
I did never have any need for it in the last couple years :-)
Bernhard
[1] https://gisgeography.com/gis-dictionary-definition-glossary/#V
[2] https://portal.opengeospatial.org/files/?artifact_id=25354 page 24
>
> On 1/8/19 9:02 AM, Havard Tveite wrote:
>> I agree that disabling the vertex tool for point layers is a good
>> idea. It will improve consistency and avoid confusion.
>> A separate tool for moving a part of a multi-geometry would be
>> useful.
>>
>> Håvard
>>
>> On 08. jan. 2019 07:53, Bernhard Ströbl wrote:
>>> Hi Saber,
>>>
>>> Delete a single point (part) in a multi-point layer with remove part
>>> tool (as you would with e.g. a multi-polygon layer).
>>> Move single point in a multi-point layer: There is no option to move
>>> a part in a multi-line or multi-polygon layer either (or I am not
>>> aware of it). Why is it different for multi-point? If there is a need
>>> to move parts in a multi-* layer, a dedicated tool should be
>>> established IMHO covering all cases.
>>>
>>> Do not misunderstand me, I really do not bother but I started
>>> thinking about the tool's behaviour for point layers during this
>>> thread and IMHO the behaviour is not consistent:
>>> 1) the tool is called _node_ but it works on _points_, too
>>> 2) It can be used to move/delete single point geometries or parts of
>>> multi-points, but it cannot be used to move parts when editing lines
>>> or polygons (neither single nor multi), furthermore for deleting
>>> parts there is another tool that does exactly the same.
>>>
>>> Bernhard
>>>
>>> Am 07.01.2019 um 16:59 schrieb Saber Razmjooei:
>>>> Hi Bernhard,
>>>>
>>>> How about multi-point layer? All the features will move/delete with
>>>> the other tools.
>>>>
>>>> Regards
>>>> Saber
>>>>
>>>> On Mon, 7 Jan 2019 at 15:55, Bernhard Ströbl
>>>> <bernhard.stroebl at jena.de <mailto:bernhard.stroebl at jena.de>> wrote:
>>>>
>>>> Maybe the node tool shouldn't be available when editing a point
>>>> layer?
>>>> Anything one may want to do with points can be done using the other
>>>> tools (move, delete part). I was always wondering why it is there
>>>> because AFAIU nodes are not individual features, they only exist as
>>>> part
>>>> of a line or polygon boundary, but points in a point layer are
>>>> individual features themselves.
>>>>
>>>> Bernhard
>>>>
>>>> Am 07.01.2019 um 16:25 schrieb DelazJ:
>>>> > Hi Micha,
>>>> >
>>>> > The Node Tool is not meant to remove features, but to
>>>> edit/remove
>>>> their
>>>> > geometries. Your feature persists in your dataset through their
>>>> > attributes and you can later use the "Add part" tool to
>>>> create a new
>>>> > geometry.
>>>> >
>>>> https://docs.qgis.org/testing/en/docs/user_manual/working_with_vector/editing_geometry_attributes.html#vertex-tool
>>>>
>>>> > For full deletion (data + geometry), you should use the the
>>>> "Delele
>>>> > selected" tool, with a red bin.
>>>> >
>>>> > Regards,
>>>> > Harrissou
>>>> >
>>>> > Le lun. 7 janv. 2019 à 16:15, Micha Silver <tsvibar at gmail.com
>>>> <mailto:tsvibar at gmail.com>
>>>> > <mailto:tsvibar at gmail.com <mailto:tsvibar at gmail.com>>> a écrit :
>>>> >
>>>> > Hi Alex:
>>>> >
>>>> > Linux Mint 19
>>>> >
>>>> > gdal 2.2.3
>>>> >
>>>> > QGIS 3.4.3
>>>> >
>>>> >
>>>> > Just out of curiosity, I did the same on a debian buster
>>>> machine
>>>> > (QGIS 2.18) and found the same: deleting vertices (with
>>>> the node
>>>> > tool) on a point vector layer does not delete the
>>>> attribute rows.
>>>> >
>>>> >
>>>> > On 1/6/19 11:38 PM, Alexandre Neto wrote:
>>>> >> What's your platform?
>>>> >> What's the version of gdal?
>>>> >>
>>>> >> Thanks,
>>>> >>
>>>> >> Alex Neto
>>>> >>
>>>> >> A dom, 6/01/2019, 12:55, Micha Silver <tsvibar at gmail.com
>>>> <mailto:tsvibar at gmail.com>
>>>> >> <mailto:tsvibar at gmail.com <mailto:tsvibar at gmail.com>>>
>>>> escreveu:
>>>> >>
>>>> >> I have found that after deleting some points in both a
>>>> >> shapefile and a geopackage layer, the attribute rows
>>>> remain in
>>>> >> the table (with null geometry). Is this expected?
>>>> I'm using
>>>> >> 3.4.3, and I don't remember that being so in earlier
>>>> versions.
>>>> >>
>>>> >>
>>>> >> I removed the "phantom" rows by selecting by
>>>> expression:
>>>> >> '$geometry is null' and then deleting. Still the
>>>> behavior was
>>>> >> surprising. I hope this is not a resurrection of
>>>> >> https://issues.qgis.org/issues/11007 ??
>>>> >>
>>>> >>
>>>> >> Thanks
>>>> >>
>>>> >> --
>>>> >> Micha Silver
>>>> >> Ben Gurion Univ.
>>>> >> Sde Boker, Remote Sensing Lab
>>>> >> cell: +972-523-665918
>>>> >>
>>>> >> _______________________________________________
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>>>> >> --
>>>> >> Alexandre Neto
>>>> >> ---------------------
>>>> >> @AlexNetoGeo
>>>> >> http://sigsemgrilhetas.wordpress.com
>>>> >> http://gisunchained.wordpress.com
>>>> >
>>>> > --
>>>> > Micha Silver
>>>> > Ben Gurion Univ.
>>>> > Sde Boker, Remote Sensing Lab
>>>> > cell: +972-523-665918
>>>> >
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>>>>
>>>>
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>>>>
>>>>
>>>> --
>>>> Saber Razmjooei
>>>> www.lutraconsulting.co.uk <http://www.lutraconsulting.co.uk>
>>>> +44 (0)7568 129733
>>>
>>>
>>
> --
> Matthias Kuhn
> matthias at opengis.ch <mailto:matthias at opengis.ch>
> +41 (0)76 435 67 63 <tel:+41764356763>
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