[GIS] Finding a point inside a polygon based on maximum value of a specific field

arcgis-desktoparcmappointpoint-in-polygonpolygon

I have a Polygon Shapefile that represents US counties and a Point Shapefile that represents hospitals. The hospital attributes table includes fields like "Number of Beds", "Number of Patients" and "Number of Doctors". I want to find the data for the hospital which has the maximum number of doctors in each county.

Lets say these Points fall inside county xyz.

Hospital…..Beds….Patients…Doctors

1 ……………. 20 …… 200 ………. 10

2 ……………. 12 …… 300 ………. 5

3 ……………. 15 …… 100 ………. 13

My desired result should look like:

County…..Hospital…..Beds….Patients…Doctors

xyz …………3 ……………. 15 …… 100 ………. 13

Getting just maximum of Doctors is not what I need (or maximum of all fields).

Best Answer

Note: Edited answer based on additional info provided by OP

Try the following:

1) Combine the county and hospitals datasets, either via a spatial join or with identify (I personally prefer identify so I have a new layer to work with, but either should work). This should give you a single point dataset with all your hospital info, but with the addition of the county name that it lies in.

2) Run the SORT tool to create a sorted dataset based on the county name field and the Doctor field, each sorted in decending order. If you are likely to have multiple hospitals in a county with the same number of doctors, and you have another field which would be the deciding factor in determining which hospital wins in event of that tie (ex: if 2 hospitals have the same max number of doctors, chose the one of those with the greater number of beds), then add that field as well.

3) Run the Summary Statistics tool. For the STATISTICS FIELD(S) add each field from the hospital data you want data from (ID, doctors, patients, beds), with Statistics Type = First. For CASE FIELD, select the county name (or ID). This will esentially give you the first feature for each county, and since you already sorted it to put the hospital with the max doctors at the top for each county, this should get you what you need.

Related Solutions

PostGIS Point Grid – Creating Regular Point Grid Inside Polygon in PostGIS

You do that with generate_series.

If you don't want to manually write where the grid is to start and stop, the easiest is to create a function.

I have not tested the below properly, but I think it should work:

CREATE OR REPLACE FUNCTION makegrid(geometry, integer)
RETURNS geometry AS
'SELECT ST_Collect(ST_POINT(x, y)) FROM 
generate_series(floor(ST_XMIN($1))::int, ceiling(ST_XMAX($1)-ST_XMIN($1))::int, $2) AS x,
generate_series(floor(ST_YMIN($1))::int, ceiling(ST_YMAX($1)-ST_YMIN($1))::int, $2) AS y 
WHERE st_intersects($1, ST_POINT(x, y))'
LANGUAGE sql

To use it you can do:

SELECT makegrid(the_geom, 1000) from mytable;

where the first argument is the polygon you want the grid in, and the second argument is the distance between the points in the grid.

If you want one point per row you just use ST_Dump like:

SELECT (ST_Dump(makegrid(the_geom, 1000))).geom as the_geom from mytable;

[GIS] Find maximum and minimum value of points within a polygon buffer

I had a tool I made that basically did this, so I just tweaked it a little to fit what you need.

It's called Calculate Point Statistics, and you can download it here:

http://ianbroad.com/arcgis-toolbox-calculate-point-statistics-polygon-arcpy/

Source code:

http://ianbroad.com/download/script/CalculatePointStatistics.py

It takes an input Polygon and Point feature class and uses a selected field to find the minimum, maximum, and average of the points and adds the results to the polygon feature. It skips any null values. It will work with ArcGIS 10.1+

Here's a screenshot of the parameters: enter image description here

Best Answer

Related Solutions

PostGIS Point Grid – Creating Regular Point Grid Inside Polygon in PostGIS

[GIS] Find maximum and minimum value of points within a polygon buffer

Related Question