Minor fixex and propagate the changes into the PyAPI

Author: Radonirinaunimi

pineappl/src/boc.rs

@@ -1087,21 +1087,34 @@ impl Channel {
         })
     }
 
+    /// Finds the factor with the smallest absolute value in the channel and
+    /// divides all coefficients by this value.
+    ///
+    /// # Returns
+    ///
+    /// A tuple containing:
+    /// - the factored-out coefficient
+    /// - a new `Channel` with all coefficients divided by the factored value
+    ///
+    /// # Panics
+    ///
     /// TODO
+    #[must_use]
     pub fn factor(&self) -> (f64, Self) {
         let factor = self
             .entry
             .iter()
-            .map(|(_, f)| f.abs())
+            .map(|(_, f)| *f)
             .min_by(|a, b| {
-                a.partial_cmp(b)
+                a.abs()
+                    .partial_cmp(&b.abs())
                     // UNWRAP: if we can't compare the numbers the data structure is bugged
                     .unwrap()
             })
             // UNWRAP: every `Channel` has at least one entry
             .unwrap();
 
-        let new_channel = Channel::new(
+        let new_channel = Self::new(
             self.entry
                 .iter()
                 .cloned()

pineappl/src/fk_table.rs

@@ -108,6 +108,12 @@ impl FkTable {
         &self.grid
     }
 
+    /// Returns a mutable reference to the [`Grid`] object for this `FkTable`.
+    #[must_use]
+    pub fn grid_mut(&mut self) -> &mut Grid {
+        &mut self.grid
+    }
+
     // TODO: when trying to convert the following function to `const` as per clippy's suggestion,
     // the compiler errors out with: 'the destructor for this type cannot be evaluated in constant
     // functions'

pineappl/src/grid.rs

@@ -1484,7 +1484,10 @@ impl Grid {
             .collect();
     }
 
-    /// TODO
+    /// Merges the factors of the channels into the subgrids to normalize channel coefficients.
+    ///
+    /// This method factors out the smallest absolute coefficient from each channel using
+    /// [`boc::Channel::factor`] and then scales the corresponding subgrids by these factors.
     pub fn merge_channel_factors(&mut self) {
         let (factors, new_channels): (Vec<_>, Vec<_>) =
             self.channels().iter().map(Channel::factor).unzip();

pineappl_py/src/fk_table.rs

@@ -224,12 +224,18 @@ impl PyFkTable {
     /// ----------
     /// pid_basis: PyPidBasis
     ///     PID basis of the resulting FK Table
-    pub fn rotate_pid_basis(&mut self, pid_basis: PyPidBasis) -> PyGrid {
-        let mut grid_mut = self.fk_table.grid().clone();
-        grid_mut.rotate_pid_basis(pid_basis.into());
-        PyGrid {
-            grid: grid_mut.clone(),
-        }
+    pub fn rotate_pid_basis(&mut self, pid_basis: PyPidBasis) {
+        self.fk_table.grid_mut().rotate_pid_basis(pid_basis.into());
+    }
+
+    /// Merge the factors of all the channels.
+    pub fn merge_channel_factors(&mut self) {
+        self.fk_table.grid_mut().merge_channel_factors();
+    }
+
+    /// Splits the grid such that each channel contains only a single tuple of PIDs.
+    pub fn split_channels(&mut self) {
+        self.fk_table.grid_mut().split_channels();
     }
 
     /// Write to file.