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less conditionals in bend_attrs

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Motiejus Jakštys 2021-04-06 07:16:00 +03:00
parent 0d805d1be6
commit fdc7835535
1 changed files with 17 additions and 19 deletions
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34
IV/wm.sql
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@ -265,28 +265,26 @@ drop function if exists bend_attrs;
drop type if exists t_bend_attrs;
create type t_bend_attrs as (
bend geometry,
area real,
cmp real,
adjsize real,
baselinelength real
area real not null default 0,
cmp real not null default 0,
adjsize real not null default 0,
baselinelength real not null default 0
);
create function bend_attrs(bends geometry[], dbgname text default null) returns setof t_bend_attrs as $$
declare
fourpi constant real default 4*radians(180);
i int4;
fourpi real;
polygon geometry;
bend geometry;
res t_bend_attrs;
begin
fourpi = 4*radians(180);
for i in 1..array_length(bends, 1) loop
res = null;
bend = bends[i];
if st_numpoints(bend) < 3 then
polygon = null;
else
select st_makepolygon(st_addpoint(bend, st_startpoint(bend))) into polygon;
select st_distance(st_startpoint(bend), st_endpoint(bend)) into res.baselinelength;
res = null;
res.bend = bend;
if st_numpoints(bend) >= 3 then
polygon = st_makepolygon(st_addpoint(bend, st_startpoint(bend)));
res.baselinelength = st_distance(st_startpoint(bend), st_endpoint(bend));
-- Compactness Index (cmp) is defined as "the ratio of the area of the
-- polygon over the circle whose circumference length is the same as the
-- length of the circumference of the polygon". I assume they meant the
@ -295,13 +293,11 @@ begin
-- 2. get polygon perimeter = u. Pretend it's our circle's circumference.
-- 3. get A (area) of the circle from u: A = (u^2)/(4*pi)
-- 4. divide P by A: cmp = P/A = P/((u^2)*4*pi) = 4*pi*P/u^2
select st_area(polygon) into res.area;
select fourpi*res.area/(st_perimeter(polygon)^2) into res.cmp;
select bend into res.bend;
res.area = st_area(polygon);
res.cmp = fourpi*res.area/(st_perimeter(polygon)^2);
if res.cmp > 0 then
res.adjsize = (res.area*(0.75/res.cmp));
end if;
if res.area > 0 then
select (res.area*(0.75/res.cmp)) into res.adjsize;
end if;
if dbgname is not null then
@ -318,7 +314,9 @@ begin
)
);
end if;
return next res;
end loop;
end;
$$ language plpgsql;