[Qgis-user] spatialjoin
Bernd Vogelgesang
bernd.vogelgesang at gmx.de
Thu Dec 22 16:39:59 PST 2016
Am 22.12.2016, 09:26 Uhr, schrieb Laurent Bourlet
<laurentbourlet34 at gmail.com>:
>
> Hi at all
>
> i succeed !! thank's at all ...Andrew was right ... but i add an another
> thing ; i have indicated in the dialogue box , under >"default value" ,
> in "relational value" the name of the layer B , the right field etc...
> and now it's ok !
>
> one more time , thank's !!
>
> laurent
Great!
Now it would would be nice if you would post a little walk-trough, so
"old-fashioned" people like me have a chance to benefit from this a well.
Cheers
Bernd
>
>
> Le 21/12/2016 à 23:32, Andrew a écrit :
>> Regarding the default values option/limitations, I can add that if you
>> try to use the default values expression dialog >>to build an
>> expression using geomintersects() the dialog will evaluate the
>> expression as invalid. Instead, build the >>expression in the field
>> calculator and then copy/paste it into default value box and skip using
>> the expression dialog.
>>
>> Andrew
>>
>> On Wed, Dec 21, 2016 at 1:32 PM, DelazJ <delazj at gmail.com> wrote:
>>> Hi,
>>> Laurent, I can think about different ways you can test to tackle your
>>> issues, provided you have two spatial layers >>>that overlap (and
>>> without any intermediate layer creation):
>>> - recent QGIS introduce default values concept
>>> (http://docs.qgis.org/testing/en/docs/user_manual/working_with_vector/>>>vector_properties.html#common-settings)
>>> - i'm not really sure about its limitations though
>>> - add a virtual field
>>> (http://docs.qgis.org/2.14/en/docs/user_manual/working_with_vector/>>>attribute_table.html#editing-attribute-values)
>>> that you could later recalculate into a simple field
>>> - use the Autofields plugin
>>> (http://plugins.qgis.org/plugins/AutoFields/)
>>> - use the SpatialJoin plugin
>>> (http://plugins.qgis.org/plugins/spatialJoin/)
>>>
>>> Except the SpatialJoin plugin option (which is internally based on
>>> it), you'll need to write an expression likely >>>based on
>>> refFunctions plugin (e.g, geomintersects) someone mentioned above.
>>>
>>> HTH,
>>> Harrissou
>>>
>>>
>>> 2016-12-21 19:23 GMT+01:00 Laurent Bourlet
>>> <laurentbourlet34 at gmail.com>:
>>>> Hi,
>>>>
>>>> i thought it was more easy ...
>>>>
>>>> In fact , i don't use a GPS because these points don't need precision
>>>> : they are only used to identify the parcels >>>>. And i would like
>>>> to catch their identity ( a number for each parcel and the owner ) if
>>>> possible with a dynamic >>>>spatialjoin...
>>>>
>>>> With booth data ( number of parcel and name of owner ) , i could talk
>>>> with the fisc administration :-)
>>>>
>>>> Randy was right ...i didn't have the same EPSG for the two layers .
>>>> It's now OK ! but without the feature >>>>"dynamic" .
>>>>
>>>> Indeed , i would avoid building many temporaries layers and i thought
>>>> it existed a plugin for this " dynamic" >>>>feature.
>>>>
>>>> If no , i will ask my users to make spatialjoins some time to time ...
>>>>
>>>> Waiting , i will try the solution of Bernd...
>>>>
>>>> Thank you anyway !
>>>>
>>>> laurent
>>>>
>>>>
>>>> Le 21/12/2016 à 17:46, Bernd Vogelgesang a écrit :
>>>>> Hi,
>>>>>
>>>>> for me this sounds more like he is getting new points once in a
>>>>> while and
>>>>> wants to join those attributes to the new points "automatically"
>>>>> from the
>>>>> parcel layer.
>>>>>
>>>>> The biggest problem for users is to rethink the workflow from the
>>>>> end to
>>>>> the beginning and to know the limitations.
>>>>>
>>>>> The outcome should be a point layer with the polygons attributes. If
>>>>> those
>>>>> points (layer A) are from GPS as Randy assumes, they have to be
>>>>> reprojected to the parcels layer (layer B) before being able to join
>>>>> them
>>>>> spatially(layer C). The spatial join in the toolbox produces layer D.
>>>>>
>>>>> Most probably, the resulting layer D is going to to be edited in
>>>>> some way
>>>>> (adding notes about size, the progress, classifications, whatever),
>>>>> so you
>>>>> will have to find a way to preserve those new attribute while being
>>>>> able to
>>>>> add new points without much trouble.
>>>>>
>>>>> The processing toolbox is a good way to do these steps, though it
>>>>> produces
>>>>> a lot of temporary files cluttering the project.
>>>>>
>>>>> A better way for all those repetitive tasks, is to use the graphical
>>>>> modeller, to create a workflow which only has to be triggered once
>>>>> new
>>>>> points come in, and the resulting file can be saved as new a file
>>>>> e.g.
>>>>> with the current date in the name, so you have kind of an archive
>>>>> and do not
>>>>> overwrite previous files (and destroy your work in case something
>>>>> goes
>>>>> wrong).
>>>>>
>>>>> So I can imagine a model with input layer A (new points in WGS84
>>>>> without attributes) and a parcel layer B (in >>>>>whatever
>>>>> projection).
>>>>> reproject layer A and C will be created as an intermediate step.
>>>>>
>>>>> Next input layer is the latest result layer D, reprojected and with
>>>>> attributes.
>>>>> Merge layer C and D -> E. Now delete all columns which are from
>>>>> layer B (from the last spatial join. >>>>>Unfortunately, you can
>>>>> only delete one field at a time in the modeller, so you'll will have
>>>>> to add the command >>>>>several times in a row to the model) -> Fn
>>>>> Do the spatial join of Fn with B.
>>>>>
>>>>> The last result G will now hold all points with the corresponding
>>>>> parcel info plus additional fields you might >>>>>have added to the
>>>>> points.
>>>>> G will be the input D in the next run with fresh points.
>>>>>
>>>>> So, do not add new points to the already existing collection of
>>>>> points in WGS84 (it is never save to edit layers >>>>>without
>>>>> backup), but just import them as a new input set and then run the
>>>>> model with the parcel layer and the >>>>>last result layer.
>>>>>
>>>>> The modeller is not as intuitive as it should be, but it can save
>>>>> you a lot of time once you managed to set up a >>>>>model.
>>>>>
>>>>> Maybe I was completely wrong analysing the problem, but maybe
>>>>> someone else has the problem that fits to my >>>>>solution ;)
>>>>> Cheers
>>>>> Bernd
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> Am 21.12.2016, 14:07 Uhr, schrieb Randal Hale
>>>>> <rjhale at northrivergeographic.com>:
>>>>>
>>>>>> 2 things:
>>>>>>
>>>>>> 1. In QGIS there is a processing toolbox (I assume you are one
>>>>>> something as new as version 2.14.8). Open it >>>>>>(it's at the top
>>>>>> -> Processing -> Toolbox). You can search for tools. Search for
>>>>>> "join" and you should see a >>>>>>"Join Attributes by location".
>>>>>> This is a spatial join.
>>>>>>
>>>>>> 2. THE MOST IMPORTANT THING. You mentioned you had collected points
>>>>>> with a GPS. Possibly these points are in >>>>>>EPSG:4326. I'm going
>>>>>> to guess that your parcel layer isn't. If you right click your
>>>>>> parcel layer (in the layers >>>>>>panel) it will allow you to
>>>>>> select properties. On the General Tab you will see the Coordinate
>>>>>> Reference System >>>>>>mentioned and many times it is something
>>>>>> like EPSG:xxxx . A Spatial Join must have the layers in the same
>>>>>> >>>>>>coordinate system.
>>>>>>
>>>>>> If it is different - Right Click on your GPS points and "Save as".
>>>>>> When the "Save vector layer as...." window >>>>>>comes up. Save it
>>>>>> as a shapefile and MOST IMPORTANTLY change the CRS to match your
>>>>>> parcel layer. Click on the >>>>>>small globe (that appears to be
>>>>>> wearing a hat) and in the filter type in the number you see for
>>>>>> your parcels. >>>>>>You can then select that projection and Save
>>>>>> your file. It should save. You can then perform the "join by
>>>>>> >>>>>>location".
>>>>>>
>>>>>> It should work. You are very close though so don't worry.
>>>>>>
>>>>>> Randy
>>>>>>
>>>>>>
>>>>>>
>>>>>> On 12/21/2016 01:24 AM, Erwan Conseil wrote:
>>>>>>> Hi
>>>>>>> In my layer B , I have the name of the owner and the number of the
>>>>>>> parcel : this number , a polygon , have a >>>>>>>WKT location .
>>>>>>> All this is in a SHP . As I grab points in layer A directly in
>>>>>>> Qgis (2.18) , I have also a SHP >>>>>>>. And i need a dynamic join
>>>>>>> because I have no desire to make the spatial join each time...
>>>>>>> Regards
>>>>>>> Laurent
>>>>>>>
>>>>>>>> Le 21 déc. 2016 à 01:30, Randal Hale
>>>>>>>> <rjhale at northrivergeographic.com> a écrit :
>>>>>>>>
>>>>>>>> In your layer B - Do the Names of the Owners have a location
>>>>>>>> (like a tax parcel) or are they a spreadsheet >>>>>>>>(like
>>>>>>>> Microsoft Excel)?
>>>>>>>>
>>>>>>>> Randy
>>>>>>>>
>>>>>>>>
>>>>>>>>> On 12/20/2016 06:03 PM, Laurent Bourlet wrote:
>>>>>>>>> Hi at all
>>>>>>>>>
>>>>>>>>> I'm a beginner in Qgis and i would make a dynamic spatialjoin.
>>>>>>>>> In fact , i have created a vector layer ( for example A) and i
>>>>>>>>> grab points in it when I'm outdoor >>>>>>>>>( these points are
>>>>>>>>> buildings unknowned by the government and so these building are
>>>>>>>>> not taxed ...) . I >>>>>>>>>have also a layer (B) with the name
>>>>>>>>> of the owners of these lands .
>>>>>>>>> You see what i would ?...
>>>>>>>>> I would have these names transferred as attribut from B to A .
>>>>>>>>> For that , i think about a spatialjoin with a dynamic feature .
>>>>>>>>> So i have downloaded the two plugins >>>>>>>>>"reffunction" and
>>>>>>>>> "spatialjoin".
>>>>>>>>> But i have certainly maked something wrong because i don't
>>>>>>>>> succeed ...
>>>>>>>>>
>>>>>>>>> Is it the good method ?
>>>>>>>>>
>>>>>>>>> And If yes , and if exist a doc about these plugins ...i'll take
>>>>>>>>> it :-))
>>>>>>>>>
>>>>>>>>> regards
>>>>>>>>>
>>>>>>>>> Laurent
>>>>>>>>>
>>>>>>>>> ( pour les francophones ...je repère et saisis des points
>>>>>>>>> représentants des batiments construits et >>>>>>>>>visibles par
>>>>>>>>> Google Map mais inconnus par le cadastre et donc les impôts
>>>>>>>>> ...je voudrais donc enrichir la >>>>>>>>>couche de saisie par
>>>>>>>>> les références des parcelles et les noms des propriétaires par
>>>>>>>>> une jointure spatiale >>>>>>>>>dynamique ..à chaque point saisi
>>>>>>>>> , "monte" cette référence )
>>>>>>>>>
>>>>>>>>> _______________________________________________
>>>>>>>>> Qgis-user mailing list
>>>>>>>>> Qgis-user at lists.osgeo.org
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>>>>>>>> -- -----------------
>>>>>>>> Randal Hale
>>>>>>>> North River Geographic Systems, Inc
>>>>>>>> http://www.northrivergeographic.com
>>>>>>>> 423.653.3611 rjhale at northrivergeographic.com
>>>>>>>> twitter:rjhale
>>>>>>>>
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>>>>>
>>>>>
>>>>
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>
--
Bernd Vogelgesang
Siedlerstraße 2
91083 Baiersdorf/Igelsdorf
Tel: 09133-825374
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