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Using ST_DWithin to see duplicates
Fastest way to remove matched pointsFinding poi using st_dwithin in postgisST_Dwithin Source CodeST_DWithin matches wrong pointsCombining ST_DWithin and ST_IntersectsPostGIS ST_DWithin negative distanceST_DWithin Optimization PostgisRemoving duplicates in lines using PostGIS?Using ST_DWithin()Renaming duplicates in PostGIS?
I tried it this way but I think using DWithin might be better for this situation. What would be the correct order to find duplicates which exist within 10km from each other?
SELECT n, ST_ClusterDBSCAN(geog::geometry, eps := .08, minpoints := 2) over () AS cid
from (
select *
from cities as t
inner join
(select n dn
from cities as t
group by n
having count(*) >= 2) dups
on dups.dn = t.n
order by t.n
) d
EDIT: I guess I would have to do something like this:
select * from (SELECT *
from (
select *, ROW_NUMBER() OVER(order by t.n) as rownum
from cities as t
inner join
(select n dn
from cities as t
group by n
having count(*) = 2
) dups
on dups.dn = t.n
order by t.n
) d
where mod(rownum,2) = 0) even,
(SELECT *
from (
select *, ROW_NUMBER() OVER(order by t.n) as rownum
from cities as t
inner join
(select n dn
from cities as t
group by n
having count(*) = 2
) dups
on dups.dn = t.n
order by t.n
) d
where mod(rownum,1) = 0
) odd
where st_dwithin(even.geog,odd.geog,5000)
but this is confusing... maybe it's better to just to do DWithin first but I'm not sure how to do that.
postgis
asked 1 hour ago
jakscojaksco
83
add a comment |
I tried it this way but I think using DWithin might be better for this situation. What would be the correct order to find duplicates which exist within 10km from each other?
SELECT n, ST_ClusterDBSCAN(geog::geometry, eps := .08, minpoints := 2) over () AS cid
from (
select *
from cities as t
inner join
(select n dn
from cities as t
group by n
having count(*) >= 2) dups
on dups.dn = t.n
order by t.n
) d
EDIT: I guess I would have to do something like this:
select * from (SELECT *
from (
select *, ROW_NUMBER() OVER(order by t.n) as rownum
from cities as t
inner join
(select n dn
from cities as t
group by n
having count(*) = 2
) dups
on dups.dn = t.n
order by t.n
) d
where mod(rownum,2) = 0) even,
(SELECT *
from (
select *, ROW_NUMBER() OVER(order by t.n) as rownum
from cities as t
inner join
(select n dn
from cities as t
group by n
having count(*) = 2
) dups
on dups.dn = t.n
order by t.n
) d
where mod(rownum,1) = 0
) odd
where st_dwithin(even.geog,odd.geog,5000)
but this is confusing... maybe it's better to just to do DWithin first but I'm not sure how to do that.
postgis
asked 1 hour ago
jakscojaksco
83
Please add more context to your question. You have triedST_ClusterDBSCANto find duplicates, correct? Show us the selectST_DWITHINstatement you would use. If you find a duplicate, which one do you want to keep, and which one should be deleted, or do you want to delete both of them?
– Michael
27 mins ago
I'd like to keep the one with the least null values and I'd like to copy theicolumn's value to the other row before deleting
– jaksco
6 mins ago
add a comment |
I tried it this way but I think using DWithin might be better for this situation. What would be the correct order to find duplicates which exist within 10km from each other?
SELECT n, ST_ClusterDBSCAN(geog::geometry, eps := .08, minpoints := 2) over () AS cid
from (
select *
from cities as t
inner join
(select n dn
from cities as t
group by n
having count(*) >= 2) dups
on dups.dn = t.n
order by t.n
) d
EDIT: I guess I would have to do something like this:
select * from (SELECT *
from (
select *, ROW_NUMBER() OVER(order by t.n) as rownum
from cities as t
inner join
(select n dn
from cities as t
group by n
having count(*) = 2
) dups
on dups.dn = t.n
order by t.n
) d
where mod(rownum,2) = 0) even,
(SELECT *
from (
select *, ROW_NUMBER() OVER(order by t.n) as rownum
from cities as t
inner join
(select n dn
from cities as t
group by n
having count(*) = 2
) dups
on dups.dn = t.n
order by t.n
) d
where mod(rownum,1) = 0
) odd
where st_dwithin(even.geog,odd.geog,5000)
but this is confusing... maybe it's better to just to do DWithin first but I'm not sure how to do that.
postgis
asked 1 hour ago
jakscojaksco
83
I tried it this way but I think using DWithin might be better for this situation. What would be the correct order to find duplicates which exist within 10km from each other?
SELECT n, ST_ClusterDBSCAN(geog::geometry, eps := .08, minpoints := 2) over () AS cid
from (
select *
from cities as t
inner join
(select n dn
from cities as t
group by n
having count(*) >= 2) dups
on dups.dn = t.n
order by t.n
) d
EDIT: I guess I would have to do something like this:
select * from (SELECT *
from (
select *, ROW_NUMBER() OVER(order by t.n) as rownum
from cities as t
inner join
(select n dn
from cities as t
group by n
having count(*) = 2
) dups
on dups.dn = t.n
order by t.n
) d
where mod(rownum,2) = 0) even,
(SELECT *
from (
select *, ROW_NUMBER() OVER(order by t.n) as rownum
from cities as t
inner join
(select n dn
from cities as t
group by n
having count(*) = 2
) dups
on dups.dn = t.n
order by t.n
) d
where mod(rownum,1) = 0
) odd
where st_dwithin(even.geog,odd.geog,5000)
but this is confusing... maybe it's better to just to do DWithin first but I'm not sure how to do that.
postgis
postgis
asked 1 hour ago
jakscojaksco
83
asked 1 hour ago
jakscojaksco
83
edited 11 mins ago
jaksco
asked 1 hour ago
jakscojaksco
83
asked 1 hour ago
jakscojaksco
83
asked 1 hour ago
jakscojaksco
83
83
Please add more context to your question. You have triedST_ClusterDBSCANto find duplicates, correct? Show us the selectST_DWITHINstatement you would use. If you find a duplicate, which one do you want to keep, and which one should be deleted, or do you want to delete both of them?
– Michael
27 mins ago
I'd like to keep the one with the least null values and I'd like to copy theicolumn's value to the other row before deleting
– jaksco
6 mins ago
add a comment |
Please add more context to your question. You have triedST_ClusterDBSCANto find duplicates, correct? Show us the selectST_DWITHINstatement you would use. If you find a duplicate, which one do you want to keep, and which one should be deleted, or do you want to delete both of them?
– Michael
27 mins ago
I'd like to keep the one with the least null values and I'd like to copy theicolumn's value to the other row before deleting
– jaksco
6 mins ago
Please add more context to your question. You have tried
ST_ClusterDBSCAN to find duplicates, correct? Show us the select ST_DWITHIN statement you would use. If you find a duplicate, which one do you want to keep, and which one should be deleted, or do you want to delete both of them?– Michael
27 mins ago
Please add more context to your question. You have tried
ST_ClusterDBSCAN to find duplicates, correct? Show us the select ST_DWITHIN statement you would use. If you find a duplicate, which one do you want to keep, and which one should be deleted, or do you want to delete both of them?– Michael
27 mins ago
I'd like to keep the one with the least null values and I'd like to copy the
i column's value to the other row before deleting– jaksco
6 mins ago
I'd like to keep the one with the least null values and I'd like to copy the
i column's value to the other row before deleting– jaksco
6 mins ago
add a comment |
1 Answer
1
active
oldest
votes
If your goal is just to identify duplicate records in your data. Then you can use ST_dwithin function like this;
SELECT col1
FROM cities as c1
INNER JOIN cities c2
ON ST_dWithin(geom,10000)
WHERE c1.gid != c2.gid AND c1.col1 = c2.col2
i assumed your data is in projected coordinate system (Unit: meters) and has a unique gid column. The duplication is based on col1, it may be name or any other value which should be unique in 10km radius.
answered 4 mins ago
Shahzad BachaShahzad Bacha
1,2381820
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
If your goal is just to identify duplicate records in your data. Then you can use ST_dwithin function like this;
SELECT col1
FROM cities as c1
INNER JOIN cities c2
ON ST_dWithin(geom,10000)
WHERE c1.gid != c2.gid AND c1.col1 = c2.col2
i assumed your data is in projected coordinate system (Unit: meters) and has a unique gid column. The duplication is based on col1, it may be name or any other value which should be unique in 10km radius.
answered 4 mins ago
Shahzad BachaShahzad Bacha
1,2381820
add a comment |
If your goal is just to identify duplicate records in your data. Then you can use ST_dwithin function like this;
SELECT col1
FROM cities as c1
INNER JOIN cities c2
ON ST_dWithin(geom,10000)
WHERE c1.gid != c2.gid AND c1.col1 = c2.col2
i assumed your data is in projected coordinate system (Unit: meters) and has a unique gid column. The duplication is based on col1, it may be name or any other value which should be unique in 10km radius.
answered 4 mins ago
Shahzad BachaShahzad Bacha
1,2381820
add a comment |
If your goal is just to identify duplicate records in your data. Then you can use ST_dwithin function like this;
SELECT col1
FROM cities as c1
INNER JOIN cities c2
ON ST_dWithin(geom,10000)
WHERE c1.gid != c2.gid AND c1.col1 = c2.col2
i assumed your data is in projected coordinate system (Unit: meters) and has a unique gid column. The duplication is based on col1, it may be name or any other value which should be unique in 10km radius.
answered 4 mins ago
Shahzad BachaShahzad Bacha
1,2381820
If your goal is just to identify duplicate records in your data. Then you can use ST_dwithin function like this;
SELECT col1
FROM cities as c1
INNER JOIN cities c2
ON ST_dWithin(geom,10000)
WHERE c1.gid != c2.gid AND c1.col1 = c2.col2
i assumed your data is in projected coordinate system (Unit: meters) and has a unique gid column. The duplication is based on col1, it may be name or any other value which should be unique in 10km radius.
answered 4 mins ago
Shahzad BachaShahzad Bacha
1,2381820
answered 4 mins ago
Shahzad BachaShahzad Bacha
1,2381820
answered 4 mins ago
Shahzad BachaShahzad Bacha
1,2381820
answered 4 mins ago
Shahzad BachaShahzad Bacha
1,2381820
1,2381820
add a comment |
add a comment |
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Please add more context to your question. You have tried
ST_ClusterDBSCANto find duplicates, correct? Show us the selectST_DWITHINstatement you would use. If you find a duplicate, which one do you want to keep, and which one should be deleted, or do you want to delete both of them?– Michael
27 mins ago
I'd like to keep the one with the least null values and I'd like to copy the
icolumn's value to the other row before deleting– jaksco
6 mins ago