Function rainbow_test 

pub fn rainbow_test(
    y_json: &str,
    x_vars_json: &str,
    fraction: f64,
    method: &str,
) -> String

Performs the Rainbow test for linearity via WASM.

The Rainbow test checks whether the relationship between predictors and response is linear. A significant p-value suggests non-linearity.

Arguments

• y_json - JSON array of response variable values
• x_vars_json - JSON array of predictor arrays
• fraction - Fraction of data to use in the central subset (0.0 to 1.0, typically 0.5)
• method - Method to use: “r”, “python”, or “both” (case-insensitive, defaults to “r”)

Returns

JSON string containing test statistic, p-value, and interpretation.

Errors

Returns a JSON error object if parsing fails or domain check fails.