PostgreSQL supports distance operator <-> and as I understand it, this can be used for analyzing text (with pg_trgrm module) and geometry data type.
I do not know how you can use it with more than 1 dimension. Maybe you will have to define your own distance function or somehow convert your data to one column with text or geometry type. For example if you have table with 8 columns (8-dimensional cube):
c1 c2 c3 c4 c5 c6 c7 c8
1 0 1 0 1 0 1 2
You can convert it to:
c1 c2 c3 c4 c5 c6 c7 c8
a b a b a b a c
And then to table with one column:
c1
abababac
Then you can use (after creating gist index):
SELECT c1, c1 <-> 'ababab'
FROM test_trgm
ORDER BY c1 <-> 'ababab';
Example
Create sample data
-- Create some temporary data
-- ! Note that table are created in tmp schema (change sql to your scheme) and deleted if exists !
drop table if exists tmp.test_data;
-- Random integer matrix 100*8
create table tmp.test_data as (
select
trunc(random()*100)::int as input_variable_1,
trunc(random()*100)::int as input_variable_2,
trunc(random()*100)::int as input_variable_3,
trunc(random()*100)::int as input_variable_4,
trunc(random()*100)::int as input_variable_5,
trunc(random()*100)::int as input_variable_6,
trunc(random()*100)::int as input_variable_7,
trunc(random()*100)::int as input_variable_8
from
generate_series(1,100,1)
);
Transform input data to text
drop table if exists tmp.test_data_trans;
create table tmp.test_data_trans as (
select
input_variable_1 || ';' ||
input_variable_2 || ';' ||
input_variable_3 || ';' ||
input_variable_4 || ';' ||
input_variable_5 || ';' ||
input_variable_6 || ';' ||
input_variable_7 || ';' ||
input_variable_8 as trans_variable
from
tmp.test_data
);
This will give you one variable trans_variable where all the 8 dimensions are stored:
trans_variable
40;88;68;29;19;54;40;90
80;49;56;57;42;36;50;68
29;13;63;33;0;18;52;77
44;68;18;81;28;24;20;89
80;62;20;49;4;87;54;18
35;37;32;25;8;13;42;54
8;58;3;42;37;1;41;49
70;1;28;18;47;78;8;17
Instead of || operator you can also use the following syntax (shorter, but more cryptic):
select
array_to_string(string_to_array(t.*::text,''),'') as trans_variable
from
tmp.test_data t
Add index
create index test_data_gist_index on tmp.test_data_trans using gist(trans_variable);
Test distance
Note: I've selected one row from table - 52;42;18;50;68;29;8;55 - and used slightly changed value (42;42;18;52;98;29;8;55) to test the distance. Of course, you will have completely different values in your test data, because it is RANDOM matrix.
select
*,
trans_variable <-> '42;42;18;52;98;29;8;55' as distance,
similarity(trans_variable, '42;42;18;52;98;29;8;55') as similarity,
from
tmp.test_data_trans
order by
trans_variable <-> '52;42;18;50;68;29;8;55';
You can use distance operator <-> or similiarity function. Distance = 1 - Similarity
