series_cosine_similarity_fl()

Calculates the cosine similarity of two numerical vectors.

The function series_cosine_similarity_fl() is a user-defined function (UDF) that takes an expression containing two dynamic numerical arrays as input and calculates their cosine similarity.

Syntax

series_cosine_similarity_fl(vec1, vec2, [ vec1_size [, vec2_size ]])

Parameters

Function definition

You can define the function by either embedding its code as a query-defined function, or creating it as a stored function in your database, as follows:

Query-defined

Define the function using the following let statement. No permissions are required.

let series_cosine_similarity_fl=(vec1:dynamic, vec2:dynamic, vec1_size:real=double(null), vec2_size:real=double(null))
{
    let dp = series_dot_product(vec1, vec2);
    let v1l = iff(isnull(vec1_size), sqrt(series_dot_product(vec1, vec1)), vec1_size);
    let v2l = iff(isnull(vec2_size), sqrt(series_dot_product(vec2, vec2)), vec2_size);
    dp/(v1l*v2l)
};
// Write your query to use the function here.

Stored

Define the stored function once using the following .create function. Database User permissions are required.

.create-or-alter function with (folder = "Packages\\Series", docstring = "Calculate the Cosine similarity of 2 numerical arrays")
series_cosine_similarity_fl(vec1:dynamic, vec2:dynamic, vec1_size:real=double(null), vec2_size:real=double(null))
{
    let dp = series_dot_product(vec1, vec2);
    let v1l = iff(isnull(vec1_size), sqrt(series_dot_product(vec1, vec1)), vec1_size);
    let v2l = iff(isnull(vec2_size), sqrt(series_dot_product(vec2, vec2)), vec2_size);
    dp/(v1l*v2l)
}

Example

Query-defined

To use a query-defined function, invoke it after the embedded function definition.

let series_cosine_similarity_fl=(vec1:dynamic, vec2:dynamic, vec1_size:real=double(null), vec2_size:real=double(null))
{
    let dp = series_dot_product(vec1, vec2);
    let v1l = iff(isnull(vec1_size), sqrt(series_dot_product(vec1, vec1)), vec1_size);
    let v2l = iff(isnull(vec2_size), sqrt(series_dot_product(vec2, vec2)), vec2_size);
    dp/(v1l*v2l)
};
let s1=pack_array(0, 1);
let s2=pack_array(sqrt(2), sqrt(2));
print angle=acos(series_cosine_similarity_fl(s1, s2))/(2*pi())*360

Stored

let s1=pack_array(0, 1);
let s2=pack_array(sqrt(2), sqrt(2));
print angle=acos(series_cosine_similarity_fl(s1, s2))/(2*pi())*360

Output