From dfdd12db1faf5f0de44747e4a0074c210303fd7c Mon Sep 17 00:00:00 2001
From: Philipp Rehner <prehner@ethz.ch>
Date: Tue, 11 Jul 2023 11:26:01 +0200
Subject: [PATCH] Serialization and documentation of binary association records

---
 src/association/mod.rs   | 12 ++++++++++++
 src/pcsaft/parameters.rs | 18 ++++++++++++++----
 src/pcsaft/python.rs     | 28 +++-------------------------
 3 files changed, 29 insertions(+), 29 deletions(-)

diff --git a/src/association/mod.rs b/src/association/mod.rs
index 86b0ffeba..06da46f9f 100644
--- a/src/association/mod.rs
+++ b/src/association/mod.rs
@@ -93,13 +93,25 @@ impl fmt::Display for AssociationRecord {
     }
 }
 
+/// Binary association parameters.
 #[derive(Serialize, Deserialize, Clone, Copy)]
 pub struct BinaryAssociationRecord {
+    /// Cross-association association volume parameter.
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub kappa_ab: Option<f64>,
+    /// Cross-association energy parameter.
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub epsilon_k_ab: Option<f64>,
+    /// Indices of sites that the record refers to.
+    #[serde(skip_serializing_if = "is_default_site_indices")]
+    #[serde(default)]
     pub site_indices: [usize; 2],
 }
 
+fn is_default_site_indices([i, j]: &[usize; 2]) -> bool {
+    *i == 0 && *j == 0
+}
+
 impl BinaryAssociationRecord {
     pub fn new(
         kappa_ab: Option<f64>,
diff --git a/src/pcsaft/parameters.rs b/src/pcsaft/parameters.rs
index 2738b61ef..fd6a98ad5 100644
--- a/src/pcsaft/parameters.rs
+++ b/src/pcsaft/parameters.rs
@@ -6,6 +6,7 @@ use feos_core::parameter::{
 };
 use ndarray::{Array, Array1, Array2};
 use num_dual::DualNum;
+use num_traits::Zero;
 use quantity::si::{JOULE, KB, KELVIN};
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
@@ -265,9 +266,15 @@ impl PcSaftRecord {
     }
 }
 
+/// PC-SAFT binary interaction parameters.
 #[derive(Serialize, Deserialize, Clone, Default)]
 pub struct PcSaftBinaryRecord {
+    /// Binary dispersion interaction parameter
+    #[serde(skip_serializing_if = "f64::is_zero")]
+    #[serde(default)]
     pub k_ij: f64,
+    /// Binary association parameters
+    #[serde(flatten)]
     association: Option<BinaryAssociationRecord>,
 }
 
@@ -313,16 +320,19 @@ impl<T: Copy + ValueInto<f64>> FromSegmentsBinary<T> for PcSaftBinaryRecord {
 
 impl std::fmt::Display for PcSaftBinaryRecord {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "PcSaftBinaryRecord(k_ij={}", self.k_ij)?;
+        let mut tokens = vec![];
+        if !self.k_ij.is_zero() {
+            tokens.push(format!("k_ij={}", self.k_ij));
+        }
         if let Some(association) = self.association {
             if let Some(kappa_ab) = association.kappa_ab {
-                write!(f, ", kappa_ab={}", kappa_ab)?;
+                tokens.push(format!("kappa_ab={}", kappa_ab));
             }
             if let Some(epsilon_k_ab) = association.epsilon_k_ab {
-                write!(f, ", epsilon_k_ab={}", epsilon_k_ab)?;
+                tokens.push(format!("epsilon_k_ab={}", epsilon_k_ab));
             }
         }
-        write!(f, ")")
+        write!(f, "PcSaftBinaryRecord({})", tokens.join(", "))
     }
 }
 
diff --git a/src/pcsaft/python.rs b/src/pcsaft/python.rs
index 90caa218d..089f215d3 100644
--- a/src/pcsaft/python.rs
+++ b/src/pcsaft/python.rs
@@ -12,7 +12,7 @@ use pyo3::prelude::*;
 use std::convert::{TryFrom, TryInto};
 use std::sync::Arc;
 
-/// Create a set of PC-Saft parameters from records.
+/// Create a new set of PC-SAFT pure component parameters.
 #[pyclass(name = "PcSaftRecord")]
 #[pyo3(
     text_signature = "(m, sigma, epsilon_k, mu=None, q=None, kappa_ab=None, epsilon_k_ab=None, na=None, nb=None, viscosity=None, diffusion=None, thermal_conductivity=None)"
@@ -131,9 +131,6 @@ impl_pure_record!(PcSaftRecord, PyPcSaftRecord);
 impl_segment_record!(PcSaftRecord, PyPcSaftRecord);
 
 #[pyclass(name = "PcSaftBinaryRecord")]
-#[pyo3(
-    text_signature = "(pure_records, binary_records=None, substances=None, search_option='Name')"
-)]
 #[derive(Clone)]
 pub struct PyPcSaftBinaryRecord(PcSaftBinaryRecord);
 
@@ -149,30 +146,11 @@ impl PyPcSaftBinaryRecord {
     }
 }
 
+impl_json_handling!(PyPcSaftBinaryRecord);
+
 impl_binary_record!(PcSaftBinaryRecord, PyPcSaftBinaryRecord);
 
-/// Create a set of PC-SAFT parameters from records.
-///
-/// Parameters
-/// ----------
-/// pure_records : List[PureRecord]
-///     pure substance records.
-/// binary_records : List[BinaryRecord], optional
-///     binary saft parameter records
-/// substances : List[str], optional
-///     The substances to use. Filters substances from `pure_records` according to
-///     `search_option`.
-///     When not provided, all entries of `pure_records` are used.
-/// search_option : {'Name', 'Cas', 'Inchi', 'IupacName', 'Formula', 'Smiles'}, optional, defaults to 'Name'.
-///     Identifier that is used to search substance.
-///
-/// Returns
-/// -------
-/// PcSaftParameters
 #[pyclass(name = "PcSaftParameters")]
-#[pyo3(
-    text_signature = "(pure_records, binary_records=None, substances=None, search_option='Name')"
-)]
 #[derive(Clone)]
 pub struct PyPcSaftParameters(pub Arc<PcSaftParameters>);