[Qgis-user] How to create one new string-value from many other string-values?

[Aron Gergely]

I don't know what is wrong with me today. Here is the response I sent in 
private by accident. Apologies:

On 23/09/2020 13:33, Aron Gergely wrote:
> Hi Bernd,
>
> Try blogs? A web search on 'QGIS aggregate functions' used to yield me 
> some nice blog resources.
>
>
> For example from Ujaval Gandhi:
> https://spatialthoughts.com/2019/04/12/summary-aggregation-qgis/
> https://spatialthoughts.com/2019/04/19/advanced-aggregate-expressions/
>
> Not meaning to single him out of course, some other qgis contributors 
> also share great resources! ;)
>
> Best regards,
> Aron
>
> On 23/09/2020 13:08, Bernd Vogelgesang wrote:
>>
>> On 23.09.20 10:21, Bernd Vogelgesang wrote:
>>>
>>> On 23.09.20 09:04, Jan.Rutha at STADT-KOELN.DE wrote:
>>>> hi there,
>>>> I got a table with a content for streetnames. For example the street
>>>> "Mainstreet" ist separated in
>>>> 10 different rows of data (one dataset for each letter in the word
>>>> "Mainstreet").
>>>>
>>>> I would like to merge these 10 datasets to one dataset. All those
>>>> datasets have one ID - so they qgis should
>>>> be able to search for the same Id and create a new textstring with
>>>> all the leters.
>>>>
>>>> I don't know how to practicly implement my idea in QGIS. Does anyone
>>>> have an idea for me?
>>>>
>>>> Thanks a lot and I wish you all a good day!
>>>>
>>>> Jan R.
>>>>
>>>>
>>> I think you could try to use an aggregate expression in the field
>>> calculator for a new field.
>>>
>>> sth like:
>>>
>>> aggregate(
>>>  layer:= 'streets',
>>>  aggregate:='concatenate',
>>>  expression:=name,
>>>  concatenator:='',  <- 2 single quotes, not 1 double, for an empty
>>> concatenator!
>>>  filter:= ID
>>>  )
>>>
>>> I don't know if the filter for ID works in this way. Can't check that
>>> cause I do not own such "interesting" data ;)
>>>
>>> Cheers,
>>>
>>> Bernd
>>>
>>>>
>> found no way to make my initial aproach work, but this:
>>
>>  array_to_string(array_agg("street",group_by:="ID"),'','')
>>
>> in the field calculator for a new text field glues together the complete
>> street name
>>
>>
>> If someone knows a resource with more examples how to work with all
>> these great functions available, please post it.
>>
>>
>>>>
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>>>>
>>>>
>>>>
>>>>
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>
> -- 
> Email Signature Kind Regards,
>
> Aron Gergely
> +31 (0) 6 38 70 97 66
>
> *Rasterra* | www.rasterra.nl <https://www.rasterra.nl>

-- 
Email Signature Kind Regards,

Aron Gergely
+31 (0) 6 38 70 97 66

*Rasterra* | www.rasterra.nl <https://www.rasterra.nl>
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