[postgis-users] Is there a generic function to find coincident vertex?

[Simon G Greener]

Not that I am aware.

You could try wrapping something like the following SQL in a function....

with data as (
     select 0.01 as tolerance,
               ST_GeomFromText('LINESTRING(0 0 1.1,1 1.001 1.2,1 1.0005 
1.3,1 1 1.1,2 2 1.2)',0) as geom
)
select SUM(isDuplicate) as duplicateCount
   from (select case when 
ST_Distance(ST_PointN(a.geom,b.*),lead(ST_PointN(a.geom,b.*)) over 
(order by b.*)) < a.tolerance
                     then 1
                     else 0
                 end as isDuplicate
           from data as a,
                generate_series(1,ST_NumPoints(a.geom),1) as b
        ) as f;

Note that if the linestring was a compoundCurve repeated vertices are 
part of the definition.

regards

Simon

On 3/12/2021 9:46 am, Shaozhong SHI wrote:
>
> Is there a generic function to find coincident vertex and count?
>
>
> It will do the following:
>
>
> Create an array of all vertex present in a data set
>
> Iterate over and find out whether there be any coincident vertex as 
> defined by a tolerance
>
> Count all occurrences
>
>
> Regards,
>
>
> David
>
>
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