Joining point value to polygon with With statements - sql

I have loaded a function hex_grid, it works fine see here but now I have a hexagonal grid I would like to add up all the values from the overlapping centroid points from a polygon layer. I've used with statements to keep things a little tidy, both select statements work as expected, my problem occurs when joining, clearly I've done something wrong but I just can't see it, any help would be appreciated. Here's the code. The hex and points are both in the same crs.
with hex AS(
SELECT hex_grid(
1,
(ST_XMIN(sa.geom)),
(ST_YMIN(sa.geom)),
(ST_XMAX(sa.geom)),
(ST_YMAX(sa.geom)),
32635, 32635, 32635) as geom_h
FROM geodata.study_area sa),
points AS(
SELECT count(*) as count, ST_Centroid(su.geom) AS geom_p
FROM clas.survey_unit su
group by su.geom
)
SELECT hex.geom_h, points.count
FROM hex
JOIN points
ON ST_Contains(points.geom_p, hex.geom_h)
group by hex.geom_h, points.count;


ST_Contains should have the polygon first, which contains the points
ON ST_Contains(hex.geom_h,points.geom_p)

Related

Use St_ExteriorRing, or similar, to fill up 'holes' in Multipolygon geojson

I have an application that reads geojson from an external API. The geojson could be either Polygon or Multipolygon depending on the day.
These are examples of the two
Multipolygon
{"type":"MultiPolygon","coordinates":[[[[-99.51346135949517,49.00303923244011],[-100.15,47.95],[-102.31,47.45],[-108.58,46.38],[-109.18,46.08],[-111.49,44.89],[-112.76,44.42],[-114.63,43.9],[-116.74,43.72],[-118.71000000000001,42.86],[-118.87,42.36],[-118.11,42.11],[-116.35,42.63],[-115.24,42.27],[-114.45,42.12],[-112.6,42.27],[-111.36,42.76],[-110.7,42.98],[-107.75,43.9],[-106.11,43.66],[-104.91,42.66],[-104.77,41.68],[-104.04,40.6],[-103.49,39.34],[-102.87,39.26],[-102.41,38.64],[-102.31,37.41],[-101.91,36.68],[-101.2,36.36],[-100,36.46],[-98.74,38.68],[-98.39,38.95],[-97.53,39.53],[-97.02,39.44],[-96.43,39.32],[-95.05,38.49],[-93.51,37.47],[-93.13,37.15],[-91.08,35.28],[-88.52,34.63],[-86.34,34.86],[-85.31,35.74],[-84.18,36.63],[-83.04,36.79],[-81.59,36.01],[-81.13,35.08],[-80.45,34.34],[-80.32,34.26],[-79.57,33.82],[-78.81808696186206,33.27775502057361],[-78.931,32.928],[-79.294,32.69],[-79.725,32.427],[-80.061,32.203],[-80.21,32.07],[-80.436,31.966],[-80.764,31.633],[-81.09,30.74],[-80.989,30.128],[-80.765,29.498],[-80.349,28.83],[-80.197,28.552],[-80.271,28.232],[-79.788,27.148],[-79.7,26.777],[-79.766,26.228],[-79.812,25.576],[-79.965,25.158],[-80.143,24.859],[-80.331,24.705],[-80.635,24.487],[-81.054,24.361],[-81.782,24.208],[-82.816,24.169],[-83.288,24.221],[-83.28,24.513],[-83.238,24.798],[-83.163,25.012],[-82.313,25.017],[-82.368,25.134],[-82.51,25.288],[-82.632,25.453],[-81.934,25.61],[-82.143,26.09],[-82.324,26.171],[-82.535,26.48],[-82.719,26.892],[-83.105,27.532],[-83.07,27.615],[-83.183,27.781],[-83.185,28.105],[-83.156,28.373],[-83.014,28.465],[-82.99,28.551],[-83.026,28.753],[-83.273,28.827],[-83.421,29.093],[-83.625,29.29],[-83.895,29.642],[-84.073,29.73],[-84.171,29.626],[-84.467,29.438],[-85.018,29.246],[-85.336,29.335],[-85.675,29.436],[-85.767,29.696],[-85.985,29.876],[-86.462,30.068],[-87.771,29.878],[-88.406,29.863],[-88.432,29.714],[-88.695,29.394],[-88.581,29.249],[-88.619,29.022],[-88.937,28.691],[-89.175,28.63],[-89.399,28.577],[-89.712,28.693],[-89.828,28.916],[-90.102,28.755],[-90.3616055222485,28.728920906440788],[-90.59,29.18],[-90.87,30.19],[-90.74,31.24],[-90.18,31.97],[-89.72,32.76],[-90.62,34.34],[-93.28,37.05],[-95,37.73],[-96.23,37.81],[-97.39,37.44],[-98.65,36.55],[-100.01,35.09],[-101.27,34.54],[-102.23,34.53],[-103.01,34.66],[-103.73,34.32],[-103.8,33.75],[-103.99,33.41],[-104.32,32.69],[-105.35,32.06],[-105.9701240038253,31.300129741791523],[-106.325,31.547],[-106.448,31.769],[-107.166,31.772],[-107.78,31.773],[-108.182,31.777],[-108.213,31.305],[-109.08,31.308],[-109.891,31.327],[-110.732,31.321],[-111.103,31.32],[-112.189,31.67],[-112.66904089087537,31.81540516722906],[-112.7,32.69],[-111.95,33.62],[-110.88,34.28],[-109.67,34.89],[-108.43,35.58],[-107.8,36.94],[-107.19,38.87],[-106.27,40.84],[-106.23,41.55],[-106.45,42.34],[-107.19,42.6],[-109.05,42.48],[-110.95,41.14],[-112.4,40.46],[-115.28999999999999,39.87],[-117.96000000000001,39.46],[-119.89,39.24],[-121.74,39.12],[-123.06,39.74],[-123.78,41.24],[-123.28999999999999,43.33],[-121.28999999999999,45.26],[-119.8,46.42],[-118.65,47.32],[-119.25,48],[-120.4,48.34],[-121.84015239078087,48.98691337339889],[-121.659,48.986],[-120.472,48.999],[-119.253,48.999],[-117.737,49.015],[-116.09,48.994],[-114.493,48.985],[-113.116,49.003],[-111.3,48.99],[-109.984,48.991],[-109.64,48.997],[-108.993,48.996],[-107.31,48.993],[-105.605,49.009],[-103.573,48.991],[-101.079,48.988],[-99.687,49.004],[-99.51346135949517,49.00303923244011]],[[-84.43,34.91],[-86.05,34.1],[-86.37,33],[-85.19,32.64],[-84.24,32.79],[-83.28,33.27],[-82.39,33.89],[-82.05,34.63],[-82.23,35.26],[-83.17,35.46],[-84.43,34.91]]],[[[-88.87125436792684,48.17251743575732],[-88.4,47.64],[-88.31,46.8],[-88.89,45.98],[-89.68,45.43],[-90.53,43.89],[-90.58,42.8],[-90.29,42.37],[-89.65,41.69],[-88.48,41.31],[-86.62,41.26],[-83.61,41.42],[-81.71,41.54],[-80.43,42.18],[-80.35384895547264,42.36541123884922],[-80.167,42.399],[-79.353,42.673],[-78.966,42.881],[-79.194,43.433],[-78.597,43.655],[-77.369,43.615],[-76.813,43.628],[-76.377,44.151],[-75.828,44.443],[-75.494,44.756],[-74.876,45.025],[-71.551,45.021],[-71.366,45.294],[-70.884,45.379],[-70.38,45.841],[-70.319,46.114],[-70.03,46.658],[-69.251,47.478],[-68.967,47.467],[-68.967,47.24],[-68.497,47.296],[-68.287,47.417],[-67.785,47.096],[-67.744,46.598],[-67.724,45.726],[-67.403,45.548],[-67.372,45.222],[-67.182,45.297],[-67.043,45.044],[-66.976,44.938],[-66.991,44.84],[-66.86,44.821],[-67.302,44.414],[-67.279,44.152],[-67.925,43.906],[-68.184,43.802],[-68.352,43.817],[-68.538,43.761],[-68.681,43.688],[-68.902,43.581],[-69.149,43.51],[-69.388,43.422],[-69.557,43.333],[-69.738,43.3],[-69.962,43.13],[-70.094,42.939],[-70.041,42.768],[-69.908,42.491],[-69.795,42.31],[-69.595,42.133],[-69.483,42.001],[-69.443,41.721],[-69.548,41.498],[-69.488,41.199],[-69.663,41.018],[-69.946,40.916],[-70.34,40.942],[-70.838,40.931],[-71.244,40.859],[-71.608,40.77],[-72.156,40.586],[-72.567,40.462],[-72.944,40.361],[-73.2,40.303],[-73.648,40.236],[-73.751,39.803],[-73.839,39.533],[-74.085,39.198],[-74.24431116799899,39.091621252336154],[-74.72,40.43],[-74.13,41.32],[-73.27,42.18],[-73.28,42.96],[-73.69,43.37],[-75.34,43.41],[-76.08,42.83],[-76.99,42.2],[-77.99,41.95],[-79.57,41.64],[-81.97,41],[-84.85,40.86],[-88.66,40.91],[-89.93,41.4],[-91.14,41.9],[-91.69,42.6],[-92.39,43.51],[-92.06,44.4],[-91.92,45.58],[-92.15,46.97],[-92.73,48.56],[-92.72981693138672,48.56141140114221],[-92.611,48.546],[-92.049,48.36],[-91.504,48.094],[-90.835,48.281],[-90.646,48.094],[-90.054,48.116],[-89.35,47.985],[-88.87125436792684,48.17251743575732]]]]}
Polygon:
{"type":"Polygon","coordinates":[[[-95.28501052631579,48.998],[-94.58,48.27],[-92.76,47.02],[-90.19,46.11],[-88.05,46.5],[-86.48,47.07],[-85.95569942586447,47.33464695646842],[-85.896,47.31],[-84.848,46.885],[-84.707,46.516],[-84.142,46.508],[-84.043,46.128],[-83.963,46.047],[-83.859,46.044],[-83.754,46.112],[-83.517,46.102],[-83.444,45.977],[-83.53,45.879],[-83.584,45.814],[-82.528,45.336],[-82.199,44.145],[-82.103,43.62],[-82.288,43.266],[-82.307,43.137],[-82.454,42.997],[-82.483,42.619],[-82.704,42.431],[-82.729,42.36],[-83.068,42.27],[-83.189,42.064],[-83.08,41.93],[-83.103,41.858],[-82.7,41.693],[-82.32,41.713],[-81.62,42.066],[-81.185,42.216],[-80.167,42.399],[-79.353,42.673],[-78.966,42.881],[-79.194,43.433],[-78.597,43.655],[-77.369,43.615],[-76.813,43.628],[-76.377,44.151],[-75.828,44.443],[-75.494,44.756],[-75.18869307056579,44.888892498410684],[-75.38,44.11],[-75.46,41.79],[-74.54,40.67],[-73.68141943423038,40.095508592021794],[-73.751,39.803],[-73.839,39.533],[-74.085,39.198],[-74.395,38.991],[-74.504,38.814],[-74.716,38.67],[-74.701,38.442],[-74.762,38.239],[-75.086,37.666],[-75.263,37.548],[-75.356,37.334],[-75.645,36.894],[-75.371,36.199],[-75.12,35.649],[-75.166,35.243],[-75.279,34.984],[-75.429,34.931],[-75.726,34.857],[-76.265,34.375],[-76.54,34.248],[-76.776,34.354],[-76.936,34.358],[-77.521,34.032],[-77.684,33.615],[-77.95,33.516],[-78.163,33.577],[-78.569,33.483],[-78.808,33.309],[-78.931,32.928],[-79.294,32.69],[-79.725,32.427],[-80.061,32.203],[-80.21,32.07],[-80.436,31.966],[-80.764,31.633],[-81.09,30.74],[-80.989,30.128],[-80.765,29.498],[-80.349,28.83],[-80.197,28.552],[-80.271,28.232],[-79.788,27.148],[-79.7,26.777],[-79.766,26.228],[-79.812,25.576],[-79.965,25.158],[-80.143,24.859],[-80.331,24.705],[-80.635,24.487],[-81.054,24.361],[-81.782,24.208],[-82.816,24.169],[-83.288,24.221],[-83.28,24.513],[-83.238,24.798],[-83.163,25.012],[-82.313,25.017],[-82.368,25.134],[-82.51,25.288],[-82.632,25.453],[-81.934,25.61],[-82.143,26.09],[-82.324,26.171],[-82.535,26.48],[-82.719,26.892],[-83.105,27.532],[-83.07,27.615],[-83.183,27.781],[-83.185,28.105],[-83.156,28.373],[-83.014,28.465],[-82.99,28.551],[-83.026,28.753],[-83.273,28.827],[-83.421,29.093],[-83.625,29.29],[-83.895,29.642],[-84.073,29.73],[-84.171,29.626],[-84.467,29.438],[-85.018,29.246],[-85.336,29.335],[-85.675,29.436],[-85.767,29.696],[-85.985,29.876],[-86.462,30.068],[-87.771,29.878],[-88.406,29.863],[-88.432,29.714],[-88.695,29.394],[-88.581,29.249],[-88.619,29.022],[-88.937,28.691],[-89.175,28.63],[-89.399,28.577],[-89.712,28.693],[-89.828,28.916],[-90.102,28.755],[-90.54,28.711],[-90.745,28.711],[-91.083,28.732],[-91.315,28.893],[-91.556,28.983],[-91.655,29.121],[-91.742,29.058],[-92.079,29.114],[-92.164,29.181],[-92.629,29.233],[-93.243,29.441],[-93.588,29.43],[-93.777,29.35],[-93.86371715145437,29.3490574222668],[-94.43,30.11],[-95.48,32.28],[-95.9,34.79],[-97.03,36.61],[-98.25,37.5],[-99.48,37.64],[-100.37,37.51],[-100.95,36.99],[-101.57,36.09],[-102.05,35.51],[-103.01,35.26],[-103.97,35.42],[-104.89,36.02],[-105.46,36.22],[-106.3,35.84],[-104.73,33.68],[-104.99,32.67],[-106.17,32.34],[-107.24,32.43],[-107.23,31.95],[-107.16324568439407,31.771988491717522],[-107.166,31.772],[-107.78,31.773],[-108.182,31.777],[-108.213,31.305],[-109.08,31.308],[-109.891,31.327],[-110.732,31.321],[-111.103,31.32],[-111.5068844073521,31.450165324653078],[-111.32,31.76],[-110.88,32.62],[-111.06,34.11],[-110.37,35.35],[-109.05,36.35],[-108.06,37.78],[-107.21,39.63],[-105.82,41.42],[-105.1,41.94],[-105.06,42.36],[-105.26,42.78],[-105.62,43.15],[-106.56,43.87],[-107.39,44.07],[-109.01,43.9],[-111.36,43.17],[-113.32,43.43],[-114.49,43.16],[-115.82,42.89],[-116.23,42.73],[-118.37,43.02],[-120.51,43.78],[-121.1,44.75],[-119.58,46.35],[-119.09,47.98],[-119.44802702702702,48.999],[-119.253,48.999],[-117.737,49.015],[-116.09,48.994],[-114.493,48.985],[-113.116,49.003],[-111.3,48.99],[-109.984,48.991],[-109.64,48.997],[-108.993,48.996],[-107.31,48.993],[-105.605,49.009],[-103.573,48.991],[-101.079,48.988],[-99.687,49.004],[-98.242,48.996],[-96.798,48.991],[-95.874,48.998],[-95.28501052631579,48.998]],[[-90.2,32.05],[-88.72,30.79],[-88.05,30.65],[-87.21,30.8],[-86.45,31.65],[-85.88,32.11],[-85.02,32.55],[-83.71,32.58],[-82.55,33.06],[-81.69,33.45],[-81.33,34.29],[-80.13,35.88],[-79.91,37.41],[-79.69,38.28],[-80.79,38.96],[-83.11,38.16],[-85.63,38.75],[-88.01,38.14],[-90.04,37.53],[-91.48,36.43],[-92.4,35.03],[-92.58,34.06],[-91.41,32.64],[-90.2,32.05]],[[-109.65,45.06],[-100.16,42.48],[-99.01,41.67],[-97.4,38.75],[-95.53,35.91],[-94.12,35.24],[-93.06,35.66],[-90.26,38.1],[-90.85,40.46],[-92.65,43.69],[-94.58,44.37],[-98.8,44.91],[-102.84,46.18],[-110.55,46.83],[-111.85,46.61],[-112.49,46.05],[-111.89,45.39],[-109.65,45.06]]]}
The polygons almost always have a 'hole' in them, so I use:
ST_SetSRID(St_ExteriorRing(ST_GeomFromGeoJSON(mygeojson))
This works fine for Polygon but not for Multipolygon. I can understand why, as it may be a difficult task to "fill up the holes" of multiple geometries.
Is there a way to solve this so that multipolygons also can use ST_ExteriorRing (or the likes of it)? Conditional solutions are fine, I can find out which are polygons and multipolygons so the solution only needs to be for multipolygon.

One option is to ST_Dump the polygon, apply ST_ExteriorRing, and finally - if necessary - recreate the MultiPolygon with ST_Collect, e.g.
SELECT
ST_Collect(ST_MakePolygon(ST_ExteriorRing(geom)))
FROM (SELECT gid,(ST_Dump(mygeojson::geometry)).* FROM mytable) j
GROUP BY gid;
The query assumes each geometry has an identifier. In this case called gid. In case the geometries have no identifier, you might wanna create one with the window function ROW_NUMBER():
SELECT
ST_Collect(ST_MakePolygon(ST_ExteriorRing(geom)))
FROM (
SELECT
ROW_NUMBER() OVER w AS gid,
(ST_Dump(mygeojson::geometry)).*
FROM mytable
WINDOW w AS (ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW)
) j
GROUP BY gid;
It gets much shorter if you can live with Polygons ;)
SELECT
ST_MakePolygon(ST_ExteriorRing((ST_Dump(mygeojson::geometry)).geom))
FROM mytable

PostGIS find linestrings that are connected

Hi i am trying to get all linestrings that are close to the nodes of other linestring
I tried:
SELECT *
FROM lines p
JOIN lines ps ON( ST_Buffer(p.geom, 0.01) && ps.geom
AND ST_Intersects(st_buffet(p.geom, 0.01), ps.geom))
But I also get lines that intersects.
There is function ST_Touches() however i can't figure out how can I add some tolerance. Maybe there is a way to make buffer over linestring nodes?

You would need to extract the nodes using st_dumpPoints, then you can join the line to these points. It is better to use st_dwithin rather than an inexact buffer.
The query would be similar to
SELECT *
FROM lines p
JOIN
(SELECT *, (ST_DumpPoints(geom)).geom
FROM lines ps) as pts
ON st_dwithin(p.geom, ps.geom, 0.1);
You might want to select something else than *, as you would get 3 geometries per row (1st line, 2 line, node of contact)
PS: regarding st_touch, the two lines can still touch each others between 2 vertices.

How to get the intersection length of touching geometries with ST_Touches

I am trying to develop a query in Postgis, where it can solve this problem:
I have a geometry and I wanna know which of the polygons that touches it, there is the highest contact area of this geometry. After I recognize this polygon I will take its value in a specific column and put this value in the same column but in my geometry.
Someone know how can I do that? I am a new user in postgresql/postgis.

As pointed out by #JGH in the comments, the overlapping area will be zero if you use ST_Touches alone. What you can do is to filter out only the geometries that do touch your reference geometry and then use ST_Intersection to get the intersection area, so that you can finally calculate the length of the intersection with ST_Length.
Data Sample
The geometry values depicted above are inside the CTE:
WITH j (id,geom) AS (
VALUES
(1,'POLYGON((-4.64 54.19,-4.59 54.19,-4.59 54.17,-4.64 54.17,-4.64 54.19))'),
(2,'POLYGON((-4.59 54.19,-4.56 54.19,-4.56 54.17,-4.59 54.17,-4.59 54.19))'),
(3,'LINESTRING(-4.65 54.19,-4.57 54.21)'),
(4,'POLYGON((-4.66 54.21,-4.60 54.21,-4.60 54.20,-4.66 54.20,-4.66 54.21))'),
(5,'POINT(-4.57 54.20)')
)
SELECT
id,
ST_Length(
ST_Intersection(
geom,
'POLYGON((-4.62 54.22,-4.58 54.22,-4.58 54.19,
-4.62 54.19,-4.62 54.22))')) AS touch_length
FROM j
WHERE
ST_Touches(
geom,
'POLYGON((-4.62 54.22,-4.58 54.22,-4.58 54.19,
-4.62 54.19,-4.62 54.22))')
ORDER BY touch_length DESC
LIMIT 1;
id | touch_length
----+---------------------
1 | 0.03000000000000025
(1 Zeile)

PostgreSQL - How to ignore gross errors when using AVG() and MAX()?

I have data in a table and I'd like to deliberately ignore some of the obviously incorrect data and take an average of the more plausible data.
Here's a simplified example of what I mean. Let's say I have a table that lists people and their height in cms.
I might use this to get the average height.....
SELECT AVG(height) FROM people;
That's fine if the data was all added correctly, but if they're (say) ten people in the database with correct heights, and one person who's height has been recorded as a billion centimeters tall then the AVG() won't return a sensible value - a classic example of GIGO (garbage in, garbage out)
Is there any way to adjust the above SQL function to ignore the outlying data points? - the data that is so different from all the rest it's got to be wrong?
I'm pretty sure the solution will involve one of the functions listed here but I'm having trouble finding some plain-english explanations of what they do and how they work.
UPDATE.......
My quoted example using height was selected for simplicity of explanation. Any proposed solution CAN'T simply filter between sensible values (i.e. height above 1.5m and below 2m) because for the actual data I'm using I don't know what the sensible values are! The solution needs to reject data that is massively different from the majority of the other data - so I guess that's where a knowledge of stats comes in handy.
Update 2) Sorry, going to have un-accept the answer I previously accepted (helpful though it was!). The standard deviation gives a value for the 'spread' of the data, but doesn't give any idea of where the outlying data is (i.e. stupidly tall people, or stupidly short people), so a clause like this...
WHERE height BETWEEN (SELECT a-2*sd FROM cte) AND (SELECT a+2*sd FROM cte);
Doesn't just remove the one stupidly tall person from one end of the range, it also removes all of the 'normal height' people from the other end of the range!
I can adjust the WHERE clause like this....
WHERE height BETWEEN (SELECT a-(sd/100) FROM cte) AND (SELECT a+(sd/100) FROM cte);
But I'm looking for a solution that doesn't require individual tweaking for each different set of data

You could use FILTER:
SELECT AVG(height) FILTER (WHERE height BETWEEN x AND y) AS avg_height
FROM people;
-- or `WHERE`:
SELECT AVG(height) AS avg_height
FROM people
WHERE height BETWEEN x AND y;
x and y are plausible values.
Alternatively you could filter out values that are outside range average() +/- 2*stddev()
WITH cte AS (
SELECT AVG(height) a, STDDEV(height) sd
FROM people
)
SELECT AVG(height)
FROM people
WHERE height BETWEEN (SELECT a-2*sd FROM cte) AND (SELECT a+2*sd FROM cte);
db<>fiddle demo

find number of polygons a line intersects

I am working with SQL Server and spatial types. Have found the very interesting. I have reached a situation and I am not sure how I might work it out. Let me outline
I have 2 points (coordinates) eg. 3,9 and 50, 20 - this is a straight line, joining such.
I have multiple polygons (50 +).
I want to be able to calculate how many polygons that the above line passes through. What I mean by pass through, when I join the 2 coordinates, how many polygons the line intersects? I want to work this out with a SQL query.
Please let me know if not clear - it is difficult to explain!

Based on your coordinates, I'm assuming geometry (as opposed to geography), but the approach should hold regardless. If you have a table dbo.Shapes that has a Shape column of type geometry and each row contains one polygon, this should do:
declare #line geometry = geometry::STLineFromText('LINESTRING(3 9, 50 20)', 0);
select count(*)
from dbo.Shapes as s
where s.shape.STIntersects(#line) = 1;
If you want to know which polygons intersect, just change the count(*) to something more appropriate.