refactor: separate keep_intervals from simplify (#647)

src/table_collection.rs

@@ -1379,16 +1379,19 @@ impl TableCollection {
 
     /// Truncate the [TableCollection] to specified genome intervals.
     ///
-    /// # Return
+    /// # Return value
     /// - `Ok(None)`: when truncation leads to empty edge table.
     /// - `Ok(Some(TableCollection))`: when trunction is successfully performed
-    /// and results in non-empty edge table.
+    /// and results in non-empty edge table. The table collection is sorted.
     /// - `Error(TskitError)`: Any errors from the C API propagate. An
     /// [TskitError::RangeError] will occur when `intervals` are not
-    /// sorted. Note that as `tskit` currently does not support `simplify`
-    /// on [TableCollection] with a non-empty migration table, calling
-    /// `keep_intervals` on those [TableCollection] with `simplify` set to
-    /// `true` will return an error.
+    /// sorted.
+    ///
+    /// # Notes
+    ///
+    /// - There is no option to simplify the output value.
+    ///   Do so manually if desired.
+    ///   Encapsulate the procedure if necessary.
     ///
     /// # Example
     /// ```rust
@@ -1414,14 +1417,13 @@ impl TableCollection {
     /// # tables.build_index().unwrap();
     /// #
     /// let intervals = [(0.0, 10.0), (90.0, 100.0)].into_iter();
-    /// tables.keep_intervals(intervals, true).unwrap().unwrap();
+    /// tables.keep_intervals(intervals).unwrap().unwrap();
     /// ```
     ///
     /// Note that no new provenance will be appended.
     pub fn keep_intervals<P>(
         self,
         intervals: impl Iterator<Item = (P, P)>,
-        simplify: bool,
     ) -> Result<Option<Self>, TskitError>
     where
         P: Into<Position>,
@@ -1565,12 +1567,6 @@ impl TableCollection {
         // sort tables
         tables.full_sort(TableSortOptions::default())?;
 
-        // simplify tables
-        if simplify {
-            let samples = tables.samples_as_vector();
-            tables.simplify(samples.as_slice(), SimplificationOptions::default(), false)?;
-        }
-
         // return None when edge table is empty
         if tables.edges().num_rows() == 0 {
             Ok(None)

src/test_fixtures.rs

@@ -519,7 +519,7 @@ mod keep_intervals {
         for intervals in intervals_lst {
             let add_migration_table = false;
             let trees = generate_simple_treesequence(add_migration_table);
-            let res = trees.keep_intervals(intervals.into_iter(), true);
+            let res = trees.keep_intervals(intervals.into_iter());
             assert!(res.is_err());
         }
     }
@@ -529,27 +529,13 @@ mod keep_intervals {
         let intervals = [(10.0, 20.0)];
 
         let add_migration_table = true;
-        let to_simplify = true;
         let trees = generate_simple_treesequence(add_migration_table);
-        let res = trees.keep_intervals(intervals.iter().copied(), to_simplify);
-        assert!(res.is_err());
-
-        let add_migration_table = true;
-        let to_simply = false;
-        let trees = generate_simple_treesequence(add_migration_table);
-        let res = trees.keep_intervals(intervals.iter().copied(), to_simply);
-        assert!(res.is_ok());
-
-        let add_migration_table = false;
-        let to_simply = true;
-        let trees = generate_simple_treesequence(add_migration_table);
-        let res = trees.keep_intervals(intervals.iter().copied(), to_simply);
+        let res = trees.keep_intervals(intervals.iter().copied());
         assert!(res.is_ok());
 
         let add_migration_table = false;
-        let to_simply = false;
         let trees = generate_simple_treesequence(add_migration_table);
-        let res = trees.keep_intervals(intervals.iter().copied(), to_simply);
+        let res = trees.keep_intervals(intervals.iter().copied());
         assert!(res.is_ok());
     }
 
@@ -573,20 +559,23 @@ mod keep_intervals {
                 .unwrap();
 
                 if exepected.edges().num_rows() > 0 {
-                    let truncated = full_trees
-                        .keep_intervals(intervals.iter().copied(), true)
+                    let mut truncated = full_trees
+                        .keep_intervals(intervals.iter().copied())
                         .expect("error")
                         .expect("empty table");
+                    let samples = truncated.samples_as_vector();
+                    assert!(truncated.edges().num_rows() > 0);
+                    truncated
+                        .simplify(&samples, crate::SimplificationOptions::default(), false)
+                        .expect("error simplifying");
 
                     // dump tables for comparision
-                    let truncated = truncated.dump_tables().unwrap();
                     let expected = exepected.dump_tables().unwrap();
-
                     let res = truncated.equals(&expected, TableEqualityOptions::all());
                     assert!(res);
                 } else {
                     let trucated = full_trees
-                        .keep_intervals(intervals.iter().copied(), true)
+                        .keep_intervals(intervals.iter().copied())
                         .unwrap();
                     assert!(trucated.is_none());
                 }

src/trees/treeseq.rs

@@ -346,15 +346,19 @@ impl TreeSequence {
 
     /// Truncate the [TreeSequence] to specified genome intervals.
     ///
+    /// # Return value
     /// - `Ok(None)`: when truncation leads to empty edge table.
     /// - `Ok(Some(TableCollection))`: when trunction is successfully performed
-    /// and results in non-empty edge table.
+    /// and results in non-empty edge table. The tables are sorted.
     /// - `Error(TskitError)`: Any errors from the C API propagate. An
     /// [TskitError::RangeError] will occur when `intervals` are not
-    /// sorted. Note that as `tskit` currently does not support `simplify`
-    /// on [TreeSequence] with a non-empty migration table, calling
-    /// `keep_intervals` on those [TreeSequence] with `simplify` set to `true`
-    /// will return an error.
+    /// sorted.
+    ///
+    /// # Notes
+    ///
+    /// - There is no option to simplify the output value.
+    ///   Do so manually if desired.
+    ///   Encapsulate the procedure if necessary.
     ///
     /// # Example
     /// ```rust
@@ -382,26 +386,22 @@ impl TreeSequence {
     ///  # let trees = TreeSequence::new(tables, TreeSequenceFlags::default()).unwrap();
     ///  #
     ///  let intervals = [(0.0, 10.0), (90.0, 100.0)].into_iter();
-    ///  trees.keep_intervals(intervals, true).unwrap().unwrap();
+    ///  let mut tables = trees.keep_intervals(intervals).unwrap().unwrap();
+    ///  // Conversion back to tree sequence requires the usual steps
+    ///  tables.simplify(&tables.samples_as_vector(), tskit::SimplificationOptions::default(), false).unwrap();
+    ///  tables.build_index().unwrap();
+    ///  let trees = tables.tree_sequence(tskit::TreeSequenceFlags::default()).unwrap();
     /// ```
     ///
     /// Note that no new provenance will be appended.
     pub fn keep_intervals<P>(
         self,
         intervals: impl Iterator<Item = (P, P)>,
-        simplify: bool,
-    ) -> Result<Option<Self>, TskitError>
+    ) -> Result<Option<TableCollection>, TskitError>
     where
         P: Into<Position>,
     {
-        let tables = self.dump_tables()?;
-        match tables.keep_intervals(intervals, simplify) {
-            Ok(Some(tables)) => {
-                Self::new(tables, TreeSequenceFlags::default().build_indexes()).map(Some)
-            }
-            Ok(None) => Ok(None),
-            Err(e) => Err(e),
-        }
+        self.dump_tables()?.keep_intervals(intervals)
     }
 
     #[cfg(feature = "provenance")]