Apply permutation

nalgebra-sparse/src/convert/serial.rs

@@ -14,6 +14,7 @@ use crate::coo::CooMatrix;
 use crate::cs;
 use crate::csc::CscMatrix;
 use crate::csr::CsrMatrix;
+use crate::utils::apply_permutation;
 
 /// Converts a dense matrix to [`CooMatrix`].
 pub fn convert_dense_coo<T, R, C, S>(dense: &Matrix<T, R, C, S>) -> CooMatrix<T>
@@ -390,15 +391,6 @@ fn sort_lane<T: Clone>(
     apply_permutation(values_result, values, permutation);
 }
 
-// TODO: Move this into `utils` or something?
-fn apply_permutation<T: Clone>(out_slice: &mut [T], in_slice: &[T], permutation: &[usize]) {
-    assert_eq!(out_slice.len(), in_slice.len());
-    assert_eq!(out_slice.len(), permutation.len());
-    for (out_element, old_pos) in out_slice.iter_mut().zip(permutation) {
-        *out_element = in_slice[*old_pos].clone();
-    }
-}
-
 /// Given *sorted* indices and corresponding scalar values, combines duplicates with the given
 /// associative combiner and calls the provided produce methods with combined indices and values.
 fn combine_duplicates<T: Clone>(

nalgebra-sparse/src/csc.rs

@@ -535,6 +535,10 @@ fn pattern_format_error_to_csc_error(err: SparsityPatternFormatError) -> SparseF
     use SparsityPatternFormatError::*;
 
     match err {
+        DifferentValuesIndicesLengths => E::from_kind_and_msg(
+            K::InvalidStructure,
+            "Lengths of values and column indices are not equal.",
+        ),
         InvalidOffsetArrayLength => E::from_kind_and_msg(
             K::InvalidStructure,
             "Length of col offset array is not equal to ncols + 1.",

nalgebra-sparse/src/csr.rs

@@ -5,11 +5,13 @@
 use crate::cs::{CsLane, CsLaneIter, CsLaneIterMut, CsLaneMut, CsMatrix};
 use crate::csc::CscMatrix;
 use crate::pattern::{SparsityPattern, SparsityPatternFormatError, SparsityPatternIter};
+use crate::utils::{apply_permutation, first_and_last_offsets_are_ok};
 use crate::{SparseEntry, SparseEntryMut, SparseFormatError, SparseFormatErrorKind};
 
 use nalgebra::Scalar;
 use num_traits::One;
 
+use num_traits::Zero;
 use std::slice::{Iter, IterMut};
 
 /// A CSR representation of a sparse matrix.
@@ -184,20 +186,40 @@ impl<T> CsrMatrix<T> {
         row_offsets: Vec<usize>,
         col_indices: Vec<usize>,
         values: Vec<T>,
-    ) -> Result<Self, SparseFormatError> {
-        use nalgebra::base::helper;
+    ) -> Result<Self, SparseFormatError>
+    where
+        T: Scalar + Zero,
+    {
         use SparsityPatternFormatError::*;
-        if helper::first_and_last_offsets_are_ok(&row_offsets, &col_indices) {
-            let mut sorted_col_indices = col_indices.clone();
-            for (index, &offset) in row_offsets[0..row_offsets.len() - 1].iter().enumerate() {
-                sorted_col_indices[offset..row_offsets[index + 1]].sort_unstable();
+
+        let mut p: Vec<usize> = (0..col_indices.len()).collect();
+
+        if col_indices.len() != values.len() {
+            return (Err(DifferentValuesIndicesLengths)).map_err(pattern_format_error_to_csr_error);
         }
+
+        if first_and_last_offsets_are_ok(&row_offsets, &col_indices) {
+            for (index, &offset) in row_offsets[0..row_offsets.len() - 1].iter().enumerate() {
+                p[offset..row_offsets[index + 1]].sort_by(|a, b| {
+                    let x = &col_indices[*a];
+                    let y = &col_indices[*b];
+                    x.partial_cmp(y).unwrap()
+                });
+            }
+
+            // permute indices
+            let sorted_col_indices: Vec<usize> = p.iter().map(|i| col_indices[*i]).collect();
+
+            // permute values
+            let mut output: Vec<T> = vec![T::zero(); p.len()];
+            apply_permutation(&mut output[..p.len()], &values[..p.len()], &p[..p.len()]);
+
             return Self::try_from_csr_data(
                 num_rows,
                 num_cols,
                 row_offsets,
                 sorted_col_indices,
-                values,
+                output,
             );
         }
         return (Err(InvalidOffsetFirstLast)).map_err(pattern_format_error_to_csr_error);
@@ -568,6 +590,10 @@ fn pattern_format_error_to_csr_error(err: SparsityPatternFormatError) -> SparseF
     use SparsityPatternFormatError::*;
 
     match err {
+        DifferentValuesIndicesLengths => E::from_kind_and_msg(
+            K::InvalidStructure,
+            "Lengths of values and column indices are not equal.",
+        ),
         InvalidOffsetArrayLength => E::from_kind_and_msg(
             K::InvalidStructure,
             "Length of row offset array is not equal to nrows + 1.",

nalgebra-sparse/src/lib.rs

@@ -149,6 +149,7 @@ pub mod csr;
 pub mod factorization;
 pub mod ops;
 pub mod pattern;
+pub mod utils;
 
 pub(crate) mod cs;
 

nalgebra-sparse/src/pattern.rs

@@ -1,5 +1,6 @@
 //! Sparsity patterns for CSR and CSC matrices.
 use crate::cs::transpose_cs;
+use crate::utils::first_and_last_offsets_are_ok;
 use crate::SparseFormatError;
 use std::error::Error;
 use std::fmt;
@@ -125,7 +126,6 @@ impl SparsityPattern {
         major_offsets: Vec<usize>,
         minor_indices: Vec<usize>,
     ) -> Result<Self, SparsityPatternFormatError> {
-        use nalgebra::base::helper;
         use SparsityPatternFormatError::*;
 
         if major_offsets.len() != major_dim + 1 {
@@ -133,7 +133,7 @@ impl SparsityPattern {
         }
 
         // Check that the first and last offsets conform to the specification
-        if !helper::first_and_last_offsets_are_ok(&major_offsets, &minor_indices) {
+        if !first_and_last_offsets_are_ok(&major_offsets, &minor_indices) {
             return Err(InvalidOffsetFirstLast);
         }
 
@@ -261,6 +261,8 @@ impl SparsityPattern {
 pub enum SparsityPatternFormatError {
     /// Indicates an invalid number of offsets.
     ///
+    /// Indicates that column indices and values have different lengths.
+    DifferentValuesIndicesLengths,
     /// The number of offsets must be equal to (major_dim + 1).
     InvalidOffsetArrayLength,
     /// Indicates that the first or last entry in the offset array did not conform to
@@ -289,7 +291,8 @@ impl From<SparsityPatternFormatError> for SparseFormatError {
         use SparsityPatternFormatError::DuplicateEntry as PatternDuplicateEntry;
         use SparsityPatternFormatError::*;
         match err {
-            InvalidOffsetArrayLength
+            DifferentValuesIndicesLengths
+            | InvalidOffsetArrayLength
             | InvalidOffsetFirstLast
             | NonmonotonicOffsets
             | NonmonotonicMinorIndices => {
@@ -310,6 +313,9 @@ impl From<SparsityPatternFormatError> for SparseFormatError {
 impl fmt::Display for SparsityPatternFormatError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
+            SparsityPatternFormatError::DifferentValuesIndicesLengths => {
+                write!(f, "Lengths of values and column indices are not equal.")
+            }
             SparsityPatternFormatError::InvalidOffsetArrayLength => {
                 write!(f, "Length of offset array is not equal to (major_dim + 1).")
             }

nalgebra-sparse/src/utils.rs

@@ -0,0 +1,23 @@
+//! Helper functions for sparse matrix computations
+
+/// Check that the first and last offsets conform to the specification of a CSR matrix
+#[inline]
+#[must_use]
+pub fn first_and_last_offsets_are_ok(
+    major_offsets: &Vec<usize>,
+    minor_indices: &Vec<usize>,
+) -> bool {
+    let first_offset_ok = *major_offsets.first().unwrap() == 0;
+    let last_offset_ok = *major_offsets.last().unwrap() == minor_indices.len();
+    return first_offset_ok && last_offset_ok;
+}
+
+/// permutes entries of in_slice according to permutation slice and puts them to out_slice
+#[inline]
+pub fn apply_permutation<T: Clone>(out_slice: &mut [T], in_slice: &[T], permutation: &[usize]) {
+    assert_eq!(out_slice.len(), in_slice.len());
+    assert_eq!(out_slice.len(), permutation.len());
+    for (out_element, old_pos) in out_slice.iter_mut().zip(permutation) {
+        *out_element = in_slice[*old_pos].clone();
+    }
+}

nalgebra-sparse/tests/unit_tests/csr.rs

@@ -178,7 +178,7 @@ fn csr_matrix_valid_data_unsorted_column_indices() {
         4,
         vec![0, 1, 2, 5],
         vec![1, 3, 2, 3, 0],
-        vec![5, 4, 1, 1, 4],
+        vec![5, 4, 1, 4, 1],
     )
     .unwrap();
 

src/base/helper.rs

@@ -29,15 +29,3 @@ where
     use std::iter;
     iter::repeat(()).map(|_| g.gen()).find(f).unwrap()
 }
-
-/// Check that the first and last offsets conform to the specification of a CSR matrix
-#[inline]
-#[must_use]
-pub fn first_and_last_offsets_are_ok(
-    major_offsets: &Vec<usize>,
-    minor_indices: &Vec<usize>,
-) -> bool {
-    let first_offset_ok = *major_offsets.first().unwrap() == 0;
-    let last_offset_ok = *major_offsets.last().unwrap() == minor_indices.len();
-    return first_offset_ok && last_offset_ok;
-}