From dc8013d6352b2498e7112a7ad11c2a111cd30834 Mon Sep 17 00:00:00 2001
From: AlessandroBregoli <alessandroxciv@gmail.com>
Date: Wed, 23 Mar 2022 16:28:17 +0100
Subject: [PATCH] Added method validate_params to ParamsTrait.

---
 src/params.rs | 54 +++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 50 insertions(+), 4 deletions(-)

diff --git a/src/params.rs b/src/params.rs
index c5a9acf..3efdc6f 100644
--- a/src/params.rs
+++ b/src/params.rs
@@ -1,16 +1,18 @@
+use enum_dispatch::enum_dispatch;
 use ndarray::prelude::*;
 use rand::Rng;
 use std::collections::{BTreeSet, HashMap};
 use thiserror::Error;
-use enum_dispatch::enum_dispatch;
 
 /// Error types for trait Params
-#[derive(Error, Debug)]
+#[derive(Error, Debug, PartialEq)]
 pub enum ParamsError {
     #[error("Unsupported method")]
     UnsupportedMethod(String),
     #[error("Paramiters not initialized")]
     ParametersNotInitialized(String),
+    #[error("Invalid cim for parameter")]
+    InvalidCIM(String),
 }
 
 /// Allowed type of states
@@ -43,6 +45,9 @@ pub trait ParamsTrait {
 
     /// Index used by discrete node to represents their states as usize.
     fn state_to_index(&self, state: &StateType) -> usize;
+
+    /// Validate parameters against domain
+    fn validate_params(&self) -> Result<(), ParamsError>;
 }
 
 /// The Params enum is the core element for building different types of nodes. The goal is to
@@ -52,7 +57,6 @@ pub enum Params {
     DiscreteStatesContinousTime(DiscreteStatesContinousTimeParams),
 }
 
-
 /// DiscreteStatesContinousTime.
 /// This represents the parameters of a classical discrete node for ctbn and it's composed by the
 /// following elements:
@@ -157,5 +161,47 @@ impl ParamsTrait for DiscreteStatesContinousTimeParams {
             StateType::Discrete(val) => val.clone() as usize,
         }
     }
-}
 
+    fn validate_params(&self) -> Result<(), ParamsError> {
+        let domain_size = self.domain.len();
+
+        // Check if the cim is initialized
+        if let None = self.cim {
+            return Err(ParamsError::ParametersNotInitialized(String::from(
+                "CIM not initialized",
+            )));
+        }
+        let cim = self.cim.as_ref().unwrap();
+        // Check if the inner dimensions of the cim are equal to the cardinality of the variable
+        if cim.shape()[1] != domain_size || cim.shape()[2] != domain_size {
+            return Err(ParamsError::InvalidCIM(format!(
+                "Incompatible shape {:?} with domain {:?}",
+                cim.shape(),
+                domain_size
+            )));
+        }
+
+        // Check if the diagonal of each cim is non-positive
+        if cim
+            .axis_iter(Axis(0))
+            .any(|x| x.diag().iter().any(|x| x >= &0.0))
+        {
+            return Err(ParamsError::InvalidCIM(String::from(
+                "The diagonal of each cim must be non-positive",
+            )));
+        }
+
+        // Check if each row sum up to 0
+        let zeros = Array::zeros(domain_size);
+        if cim
+            .axis_iter(Axis(0))
+            .any(|x| !x.sum_axis(Axis(1)).abs_diff_eq(&zeros, f64::MIN_POSITIVE))
+        {
+            return Err(ParamsError::InvalidCIM(String::from(
+                "The sum of each row must be 0",
+            )));
+        }
+
+        return Ok(());
+    }
+}