cosine

First introduced in version: 3.00.5, 3.00.4.3

Syntax

cosine(X, Y)

Compute the cosine similarity between X and Y. The cosine similarity between X and Y, is defined as (X · Y) / (||X|| × ||Y||).

Note:

Similar to the scipy.spatial.distance.cosine function in SciPy, the main difference lies in the following:

DolphinDB's cosine function calculates cosine similarity (the larger the value, the more similar), while SciPy's scipy.spatial.distance.cosine calculates cosine distance (the smaller the value, the more similar). The relationship between them is: cosine distance = 1 - cosine similarity.
cosine only accepts parameters X and Y, and does not support the weight parameter w found in scipy.spatial.distance.cosine.

X and Y are numeric vectors with the same number of elements.

A DOUBLE scalar.

x = [1, 2, 3]  
y = [4, 5, 6]  
cosine(x, y);  
// output: 0.9746318