feat: Add min parameter (#39)

src/parameters/min.rs

@@ -0,0 +1,45 @@
+use crate::metric::Metric;
+use crate::model::Model;
+use crate::parameters::{Parameter, ParameterMeta};
+use crate::scenario::ScenarioIndex;
+use std::any::Any;
+
+use crate::state::State;
+use crate::timestep::Timestep;
+use crate::PywrError;
+
+pub struct MinParameter {
+    meta: ParameterMeta,
+    metric: Metric,
+    threshold: f64,
+}
+
+impl MinParameter {
+    pub fn new(name: &str, metric: Metric, threshold: f64) -> Self {
+        Self {
+            meta: ParameterMeta::new(name),
+            metric,
+            threshold,
+        }
+    }
+}
+
+impl Parameter for MinParameter {
+    fn as_any_mut(&mut self) -> &mut dyn Any {
+        self
+    }
+    fn meta(&self) -> &ParameterMeta {
+        &self.meta
+    }
+    fn compute(
+        &self,
+        _timestep: &Timestep,
+        _scenario_index: &ScenarioIndex,
+        model: &Model,
+        state: &State,
+        _internal_state: &mut Option<Box<dyn Any + Send>>,
+    ) -> Result<f64, PywrError> {
+        let x = self.metric.get_value(model, state)?;
+        Ok(x.min(self.threshold))
+    }
+}

src/parameters/mod.rs

@@ -6,6 +6,7 @@ mod control_curves;
 mod delay;
 mod indexed_array;
 mod max;
+mod min;
 mod negative;
 mod polynomial;
 mod profiles;
@@ -33,6 +34,7 @@ pub use control_curves::{
 pub use delay::DelayParameter;
 pub use indexed_array::IndexedArrayParameter;
 pub use max::MaxParameter;
+pub use min::MinParameter;
 pub use negative::NegativeParameter;
 pub use polynomial::Polynomial1DParameter;
 pub use profiles::{DailyProfileParameter, MonthlyInterpDay, MonthlyProfileParameter, UniformDrawdownProfileParameter};

src/schema/parameters/core.rs

@@ -6,7 +6,8 @@ use crate::schema::parameters::{
 };
 use crate::{ParameterIndex, PywrError};
 use pywr_schema::parameters::{
-    ConstantParameter as ConstantParameterV1, MaxParameter as MaxParameterV1, NegativeParameter as NegativeParameterV1,
+    ConstantParameter as ConstantParameterV1, MaxParameter as MaxParameterV1, MinParameter as MinParameterV1,
+    NegativeParameter as NegativeParameterV1,
 };
 use std::collections::HashMap;
 use std::path::Path;
@@ -114,6 +115,73 @@ impl TryFromV1Parameter<MaxParameterV1> for MaxParameter {
     }
 }
 
+/// This parameter takes the minimum of another Parameter and a constant value (threshold).
+///
+/// # Arguments
+///
+/// * `parameter` - The parameter to compare with the float.
+/// * `threshold` - The threshold value to compare with the given parameter.
+///
+/// # Examples
+///
+/// ```json
+/// {
+///     "type": "Min",
+///     "parameter": {
+///         "type": "MonthlyProfile",
+///         "values": [1, 4, 5, 9, 1, 5, 10, 8, 11, 9, 11 ,12]
+///     },
+///     "threshold": 2
+/// }
+/// ```
+#[derive(serde::Deserialize, serde::Serialize, Debug, Clone)]
+pub struct MinParameter {
+    #[serde(flatten)]
+    pub meta: ParameterMeta,
+    pub parameter: DynamicFloatValue,
+    pub threshold: Option<f64>,
+}
+
+impl MinParameter {
+    pub fn node_references(&self) -> HashMap<&str, &str> {
+        HashMap::new()
+    }
+
+    pub fn add_to_model(
+        &self,
+        model: &mut crate::model::Model,
+        tables: &LoadedTableCollection,
+        data_path: Option<&Path>,
+    ) -> Result<ParameterIndex, PywrError> {
+        let idx = self.parameter.load(model, tables, data_path)?;
+        let threshold = self.threshold.unwrap_or(0.0);
+
+        let p = crate::parameters::MinParameter::new(&self.meta.name, idx, threshold);
+        model.add_parameter(Box::new(p))
+    }
+}
+
+impl TryFromV1Parameter<MinParameterV1> for MinParameter {
+    type Error = ConversionError;
+
+    fn try_from_v1_parameter(
+        v1: MinParameterV1,
+        parent_node: Option<&str>,
+        unnamed_count: &mut usize,
+    ) -> Result<Self, Self::Error> {
+        let meta: ParameterMeta = v1.meta.into_v2_parameter(parent_node, unnamed_count);
+
+        let parameter = v1.parameter.try_into_v2_parameter(Some(&meta.name), unnamed_count)?;
+
+        let p = Self {
+            meta,
+            parameter,
+            threshold: v1.threshold,
+        };
+        Ok(p)
+    }
+}
+
 #[derive(serde::Deserialize, serde::Serialize, Debug, Clone)]
 pub struct NegativeParameter {
     #[serde(flatten)]

src/schema/parameters/mod.rs

@@ -18,7 +18,7 @@ pub use super::parameters::control_curves::{
     ControlCurveIndexParameter, ControlCurveInterpolatedParameter, ControlCurveParameter,
     ControlCurvePiecewiseInterpolatedParameter,
 };
-pub use super::parameters::core::{ConstantParameter, MaxParameter, NegativeParameter};
+pub use super::parameters::core::{ConstantParameter, MaxParameter, MinParameter, NegativeParameter};
 pub use super::parameters::delay::DelayParameter;
 pub use super::parameters::indexed_array::IndexedArrayParameter;
 pub use super::parameters::polynomial::Polynomial1DParameter;
@@ -135,6 +135,7 @@ pub enum Parameter {
     MonthlyProfile(MonthlyProfileParameter),
     UniformDrawdownProfile(UniformDrawdownProfileParameter),
     Max(MaxParameter),
+    Min(MinParameter),
     Negative(NegativeParameter),
     Polynomial1D(Polynomial1DParameter),
     ParameterThreshold(ParameterThresholdParameter),
@@ -160,6 +161,7 @@ impl Parameter {
             Self::MonthlyProfile(p) => p.meta.name.as_str(),
             Self::UniformDrawdownProfile(p) => p.meta.name.as_str(),
             Self::Max(p) => p.meta.name.as_str(),
+            Self::Min(p) => p.meta.name.as_str(),
             Self::Negative(p) => p.meta.name.as_str(),
             Self::Polynomial1D(p) => p.meta.name.as_str(),
             Self::ParameterThreshold(p) => p.meta.name.as_str(),
@@ -187,6 +189,7 @@ impl Parameter {
             Self::MonthlyProfile(p) => p.node_references(),
             Self::UniformDrawdownProfile(p) => p.node_references(),
             Self::Max(p) => p.node_references(),
+            Self::Min(p) => p.node_references(),
             Self::Negative(p) => p.node_references(),
             Self::Polynomial1D(p) => p.node_references(),
             Self::ParameterThreshold(p) => p.node_references(),
@@ -231,6 +234,7 @@ impl Parameter {
             Self::MonthlyProfile(_) => "MonthlyProfile",
             Self::UniformDrawdownProfile(_) => "UniformDrawdownProfile",
             Self::Max(_) => "Max",
+            Self::Min(_) => "Min",
             Self::Negative(_) => "Negative",
             Self::Polynomial1D(_) => "Polynomial1D",
             Self::ParameterThreshold(_) => "ParameterThreshold",
@@ -263,6 +267,7 @@ impl Parameter {
             Self::MonthlyProfile(p) => ParameterType::Parameter(p.add_to_model(model, tables)?),
             Self::UniformDrawdownProfile(p) => ParameterType::Parameter(p.add_to_model(model, tables)?),
             Self::Max(p) => ParameterType::Parameter(p.add_to_model(model, tables, data_path)?),
+            Self::Min(p) => ParameterType::Parameter(p.add_to_model(model, tables, data_path)?),
             Self::Negative(p) => ParameterType::Parameter(p.add_to_model(model, tables, data_path)?),
             Self::Polynomial1D(p) => ParameterType::Parameter(p.add_to_model(model)?),
             Self::ParameterThreshold(p) => ParameterType::Index(p.add_to_model(model, tables, data_path)?),
@@ -332,7 +337,8 @@ impl TryFromV1Parameter<ParameterV1> for Parameter {
                 CoreParameter::TablesArray(p) => {
                     Parameter::TablesArray(p.try_into_v2_parameter(parent_node, unnamed_count)?)
                 }
-                CoreParameter::Min(_) | CoreParameter::Division(_) => todo!(),
+                CoreParameter::Min(p) => Parameter::Min(p.try_into_v2_parameter(parent_node, unnamed_count)?),
+                CoreParameter::Division(_) => todo!(),
             },
             ParameterV1::Custom(p) => {
                 println!("Custom parameter: {:?} ({})", p.meta.name, p.ty);