forked from M-Labs/nalgebra
598 lines
20 KiB
Rust
598 lines
20 KiB
Rust
//! An implementation of the CSR sparse matrix format.
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use crate::{SparseFormatError, SparseFormatErrorKind, SparseEntry, SparseEntryMut};
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use crate::pattern::{SparsityPattern, SparsityPatternFormatError, SparsityPatternIter};
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use crate::csc::CscMatrix;
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use crate::cs::{CsMatrix, CsLaneIterMut, CsLaneIter, CsLane, CsLaneMut};
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use nalgebra::Scalar;
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use num_traits::{One};
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use std::slice::{IterMut, Iter};
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/// A CSR representation of a sparse matrix.
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///
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/// The Compressed Sparse Row (CSR) format is well-suited as a general-purpose storage format
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/// for many sparse matrix applications.
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///
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/// TODO: Storage explanation and examples
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///
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#[derive(Debug, Clone, PartialEq, Eq)]
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pub struct CsrMatrix<T> {
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// Rows are major, cols are minor in the sparsity pattern
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pub(crate) cs: CsMatrix<T>,
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}
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impl<T> CsrMatrix<T> {
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/// Create a zero CSR matrix with no explicitly stored entries.
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pub fn new(nrows: usize, ncols: usize) -> Self {
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Self {
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cs: CsMatrix::new(nrows, ncols)
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}
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}
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/// The number of rows in the matrix.
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#[inline]
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pub fn nrows(&self) -> usize {
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self.cs.pattern().major_dim()
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}
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/// The number of columns in the matrix.
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#[inline]
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pub fn ncols(&self) -> usize {
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self.cs.pattern().minor_dim()
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}
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/// The number of non-zeros in the matrix.
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///
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/// Note that this corresponds to the number of explicitly stored entries, *not* the actual
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/// number of algebraically zero entries in the matrix. Explicitly stored entries can still
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/// be zero. Corresponds to the number of entries in the sparsity pattern.
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#[inline]
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pub fn nnz(&self) -> usize {
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self.cs.pattern().nnz()
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}
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/// The row offsets defining part of the CSR format.
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#[inline]
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pub fn row_offsets(&self) -> &[usize] {
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let (offsets, _, _) = self.cs.cs_data();
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offsets
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}
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/// The column indices defining part of the CSR format.
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#[inline]
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pub fn col_indices(&self) -> &[usize] {
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let (_, indices, _) = self.cs.cs_data();
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indices
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}
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/// The non-zero values defining part of the CSR format.
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#[inline]
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pub fn values(&self) -> &[T] {
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self.cs.values()
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}
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/// Mutable access to the non-zero values.
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#[inline]
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pub fn values_mut(&mut self) -> &mut [T] {
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self.cs.values_mut()
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}
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/// Try to construct a CSR matrix from raw CSR data.
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///
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/// It is assumed that each row contains unique and sorted column indices that are in
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/// bounds with respect to the number of columns in the matrix. If this is not the case,
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/// an error is returned to indicate the failure.
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///
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/// An error is returned if the data given does not conform to the CSR storage format.
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/// See the documentation for [CsrMatrix](struct.CsrMatrix.html) for more information.
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pub fn try_from_csr_data(
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num_rows: usize,
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num_cols: usize,
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row_offsets: Vec<usize>,
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col_indices: Vec<usize>,
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values: Vec<T>,
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) -> Result<Self, SparseFormatError> {
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let pattern = SparsityPattern::try_from_offsets_and_indices(
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num_rows, num_cols, row_offsets, col_indices)
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.map_err(pattern_format_error_to_csr_error)?;
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Self::try_from_pattern_and_values(pattern, values)
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}
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/// Try to construct a CSR matrix from a sparsity pattern and associated non-zero values.
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///
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/// Returns an error if the number of values does not match the number of minor indices
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/// in the pattern.
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pub fn try_from_pattern_and_values(pattern: SparsityPattern, values: Vec<T>)
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-> Result<Self, SparseFormatError> {
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if pattern.nnz() == values.len() {
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Ok(Self {
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cs: CsMatrix::from_pattern_and_values(pattern, values)
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})
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} else {
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Err(SparseFormatError::from_kind_and_msg(
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SparseFormatErrorKind::InvalidStructure,
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"Number of values and column indices must be the same"))
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}
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}
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/// An iterator over non-zero triplets (i, j, v).
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///
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/// The iteration happens in row-major fashion, meaning that i increases monotonically,
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/// and j increases monotonically within each row.
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///
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/// Examples
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/// --------
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/// ```
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/// # use nalgebra_sparse::csr::CsrMatrix;
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/// let row_offsets = vec![0, 2, 3, 4];
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/// let col_indices = vec![0, 2, 1, 0];
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/// let values = vec![1, 2, 3, 4];
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/// let mut csr = CsrMatrix::try_from_csr_data(3, 4, row_offsets, col_indices, values)
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/// .unwrap();
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///
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/// let triplets: Vec<_> = csr.triplet_iter().map(|(i, j, v)| (i, j, *v)).collect();
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/// assert_eq!(triplets, vec![(0, 0, 1), (0, 2, 2), (1, 1, 3), (2, 0, 4)]);
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/// ```
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pub fn triplet_iter(&self) -> CsrTripletIter<T> {
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CsrTripletIter {
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pattern_iter: self.pattern().entries(),
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values_iter: self.values().iter()
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}
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}
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/// A mutable iterator over non-zero triplets (i, j, v).
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///
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/// Iteration happens in the same order as for [triplet_iter](#method.triplet_iter).
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///
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/// Examples
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/// --------
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/// ```
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/// # use nalgebra_sparse::csr::CsrMatrix;
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/// # let row_offsets = vec![0, 2, 3, 4];
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/// # let col_indices = vec![0, 2, 1, 0];
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/// # let values = vec![1, 2, 3, 4];
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/// // Using the same data as in the `triplet_iter` example
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/// let mut csr = CsrMatrix::try_from_csr_data(3, 4, row_offsets, col_indices, values)
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/// .unwrap();
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///
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/// // Zero out lower-triangular terms
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/// csr.triplet_iter_mut()
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/// .filter(|(i, j, _)| j < i)
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/// .for_each(|(_, _, v)| *v = 0);
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///
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/// let triplets: Vec<_> = csr.triplet_iter().map(|(i, j, v)| (i, j, *v)).collect();
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/// assert_eq!(triplets, vec![(0, 0, 1), (0, 2, 2), (1, 1, 3), (2, 0, 0)]);
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/// ```
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pub fn triplet_iter_mut(&mut self) -> CsrTripletIterMut<T> {
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let (pattern, values) = self.cs.pattern_and_values_mut();
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CsrTripletIterMut {
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pattern_iter: pattern.entries(),
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values_mut_iter: values.iter_mut()
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}
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}
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/// Return the row at the given row index.
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///
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/// Panics
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/// ------
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/// Panics if row index is out of bounds.
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#[inline]
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pub fn row(&self, index: usize) -> CsrRow<T> {
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self.get_row(index)
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.expect("Row index must be in bounds")
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}
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/// Mutable row access for the given row index.
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///
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/// Panics
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/// ------
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/// Panics if row index is out of bounds.
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#[inline]
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pub fn row_mut(&mut self, index: usize) -> CsrRowMut<T> {
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self.get_row_mut(index)
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.expect("Row index must be in bounds")
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}
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/// Return the row at the given row index, or `None` if out of bounds.
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#[inline]
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pub fn get_row(&self, index: usize) -> Option<CsrRow<T>> {
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self.cs
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.get_lane(index)
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.map(|lane| CsrRow { lane })
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}
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/// Mutable row access for the given row index, or `None` if out of bounds.
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#[inline]
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pub fn get_row_mut(&mut self, index: usize) -> Option<CsrRowMut<T>> {
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self.cs
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.get_lane_mut(index)
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.map(|lane| CsrRowMut { lane })
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}
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/// An iterator over rows in the matrix.
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pub fn row_iter(&self) -> CsrRowIter<T> {
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CsrRowIter {
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lane_iter: CsLaneIter::new(self.pattern(), self.values())
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}
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}
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/// A mutable iterator over rows in the matrix.
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pub fn row_iter_mut(&mut self) -> CsrRowIterMut<T> {
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let (pattern, values) = self.cs.pattern_and_values_mut();
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CsrRowIterMut {
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lane_iter: CsLaneIterMut::new(pattern, values),
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}
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}
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/// Disassembles the CSR matrix into its underlying offset, index and value arrays.
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///
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/// If the matrix contains the sole reference to the sparsity pattern,
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/// then the data is returned as-is. Otherwise, the sparsity pattern is cloned.
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///
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/// Examples
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/// --------
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///
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/// ```
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/// # use nalgebra_sparse::csr::CsrMatrix;
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/// let row_offsets = vec![0, 2, 3, 4];
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/// let col_indices = vec![0, 2, 1, 0];
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/// let values = vec![1, 2, 3, 4];
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/// let mut csr = CsrMatrix::try_from_csr_data(
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/// 3,
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/// 4,
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/// row_offsets.clone(),
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/// col_indices.clone(),
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/// values.clone())
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/// .unwrap();
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/// let (row_offsets2, col_indices2, values2) = csr.disassemble();
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/// assert_eq!(row_offsets2, row_offsets);
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/// assert_eq!(col_indices2, col_indices);
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/// assert_eq!(values2, values);
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/// ```
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pub fn disassemble(self) -> (Vec<usize>, Vec<usize>, Vec<T>) {
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self.cs.disassemble()
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}
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/// Returns the sparsity pattern and values associated with this matrix.
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pub fn into_pattern_and_values(self) -> (SparsityPattern, Vec<T>) {
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self.cs.into_pattern_and_values()
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}
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/// Returns a reference to the sparsity pattern and a mutable reference to the values.
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#[inline]
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pub fn pattern_and_values_mut(&mut self) -> (&SparsityPattern, &mut [T]) {
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self.cs.pattern_and_values_mut()
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}
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/// Returns the underlying sparsity pattern.
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///
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/// The sparsity pattern is stored internally inside an `Arc`. This allows users to re-use
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/// the same sparsity pattern for multiple matrices without storing the same pattern multiple
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/// times in memory.
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pub fn pattern(&self) -> &SparsityPattern {
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self.cs.pattern()
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}
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/// Reinterprets the CSR matrix as its transpose represented by a CSC matrix.
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///
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/// This operation does not touch the CSR data, and is effectively a no-op.
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pub fn transpose_as_csc(self) -> CscMatrix<T> {
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let (pattern, values) = self.cs.take_pattern_and_values();
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CscMatrix::try_from_pattern_and_values(pattern, values).unwrap()
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}
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/// Returns an entry for the given row/col indices, or `None` if the indices are out of bounds.
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///
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/// Each call to this function incurs the cost of a binary search among the explicitly
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/// stored column entries for the given row.
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pub fn get_entry(&self, row_index: usize, col_index: usize) -> Option<SparseEntry<T>> {
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self.cs.get_entry(row_index, col_index)
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}
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/// Returns a mutable entry for the given row/col indices, or `None` if the indices are out
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/// of bounds.
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///
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/// Each call to this function incurs the cost of a binary search among the explicitly
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/// stored column entries for the given row.
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pub fn get_entry_mut(&mut self, row_index: usize, col_index: usize)
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-> Option<SparseEntryMut<T>> {
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self.cs.get_entry_mut(row_index, col_index)
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}
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/// Returns an entry for the given row/col indices.
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///
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/// Same as `get_entry`, except that it directly panics upon encountering row/col indices
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/// out of bounds.
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///
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/// Panics
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/// ------
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/// Panics if `row_index` or `col_index` is out of bounds.
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pub fn index_entry(&self, row_index: usize, col_index: usize) -> SparseEntry<T> {
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self.get_entry(row_index, col_index)
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.expect("Out of bounds matrix indices encountered")
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}
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/// Returns a mutable entry for the given row/col indices.
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///
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/// Same as `get_entry_mut`, except that it directly panics upon encountering row/col indices
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/// out of bounds.
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///
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/// Panics
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/// ------
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/// Panics if `row_index` or `col_index` is out of bounds.
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pub fn index_entry_mut(&mut self, row_index: usize, col_index: usize) -> SparseEntryMut<T> {
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self.get_entry_mut(row_index, col_index)
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.expect("Out of bounds matrix indices encountered")
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}
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/// Returns a triplet of slices `(row_offsets, col_indices, values)` that make up the CSR data.
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pub fn csr_data(&self) -> (&[usize], &[usize], &[T]) {
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self.cs.cs_data()
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}
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/// Returns a triplet of slices `(row_offsets, col_indices, values)` that make up the CSR data,
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/// where the `values` array is mutable.
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pub fn csr_data_mut(&mut self) -> (&[usize], &[usize], &mut [T]) {
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self.cs.cs_data_mut()
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}
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/// Creates a sparse matrix that contains only the explicit entries decided by the
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/// given predicate.
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pub fn filter<P>(&self, predicate: P) -> Self
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where
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T: Clone,
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P: Fn(usize, usize, &T) -> bool
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{
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Self { cs: self.cs.filter(|row_idx, col_idx, v| predicate(row_idx, col_idx, v)) }
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}
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/// Returns a new matrix representing the upper triangular part of this matrix.
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///
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/// The result includes the diagonal of the matrix.
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pub fn upper_triangle(&self) -> Self
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where
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T: Clone
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{
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self.filter(|i, j, _| i <= j)
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}
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/// Returns a new matrix representing the lower triangular part of this matrix.
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///
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/// The result includes the diagonal of the matrix.
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pub fn lower_triangle(&self) -> Self
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where
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T: Clone
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{
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self.filter(|i, j, _| i >= j)
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}
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/// Returns the diagonal of the matrix as a sparse matrix.
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pub fn diagonal_as_matrix(&self) -> Self
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where
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T: Clone
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{
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self.filter(|i, j, _| i == j)
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}
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}
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impl<T> CsrMatrix<T>
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where
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T: Scalar
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{
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/// Compute the transpose of the matrix.
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pub fn transpose(&self) -> CsrMatrix<T> {
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CscMatrix::from(self).transpose_as_csr()
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}
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}
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impl<T: Scalar + One> CsrMatrix<T> {
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/// TODO
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#[inline]
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pub fn identity(n: usize) -> Self {
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Self {
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cs: CsMatrix::identity(n)
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}
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}
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}
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/// Convert pattern format errors into more meaningful CSR-specific errors.
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///
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/// This ensures that the terminology is consistent: we are talking about rows and columns,
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/// not lanes, major and minor dimensions.
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fn pattern_format_error_to_csr_error(err: SparsityPatternFormatError) -> SparseFormatError {
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use SparsityPatternFormatError::*;
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use SparsityPatternFormatError::DuplicateEntry as PatternDuplicateEntry;
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use SparseFormatError as E;
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use SparseFormatErrorKind as K;
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match err {
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InvalidOffsetArrayLength => E::from_kind_and_msg(
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K::InvalidStructure,
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"Length of row offset array is not equal to nrows + 1."),
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InvalidOffsetFirstLast => E::from_kind_and_msg(
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K::InvalidStructure,
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"First or last row offset is inconsistent with format specification."),
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NonmonotonicOffsets => E::from_kind_and_msg(
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K::InvalidStructure,
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"Row offsets are not monotonically increasing."),
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NonmonotonicMinorIndices => E::from_kind_and_msg(
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K::InvalidStructure,
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"Column indices are not monotonically increasing (sorted) within each row."),
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MinorIndexOutOfBounds => E::from_kind_and_msg(
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K::IndexOutOfBounds,
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"Column indices are out of bounds."),
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PatternDuplicateEntry => E::from_kind_and_msg(
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K::DuplicateEntry,
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"Matrix data contains duplicate entries."),
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}
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}
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/// Iterator type for iterating over triplets in a CSR matrix.
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#[derive(Debug)]
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pub struct CsrTripletIter<'a, T> {
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pattern_iter: SparsityPatternIter<'a>,
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values_iter: Iter<'a, T>
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}
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impl<'a, T: Clone> CsrTripletIter<'a, T> {
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/// Adapts the triplet iterator to return owned values.
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///
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/// The triplet iterator returns references to the values. This method adapts the iterator
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/// so that the values are cloned.
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#[inline]
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pub fn cloned_values(self) -> impl 'a + Iterator<Item=(usize, usize, T)> {
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self.map(|(i, j, v)| (i, j, v.clone()))
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}
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}
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impl<'a, T> Iterator for CsrTripletIter<'a, T> {
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type Item = (usize, usize, &'a T);
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fn next(&mut self) -> Option<Self::Item> {
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let next_entry = self.pattern_iter.next();
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let next_value = self.values_iter.next();
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match (next_entry, next_value) {
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(Some((i, j)), Some(v)) => Some((i, j, v)),
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_ => None
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}
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}
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}
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/// Iterator type for mutably iterating over triplets in a CSR matrix.
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#[derive(Debug)]
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pub struct CsrTripletIterMut<'a, T> {
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pattern_iter: SparsityPatternIter<'a>,
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values_mut_iter: IterMut<'a, T>
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}
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impl<'a, T> Iterator for CsrTripletIterMut<'a, T> {
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type Item = (usize, usize, &'a mut T);
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#[inline]
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fn next(&mut self) -> Option<Self::Item> {
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let next_entry = self.pattern_iter.next();
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let next_value = self.values_mut_iter.next();
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match (next_entry, next_value) {
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(Some((i, j)), Some(v)) => Some((i, j, v)),
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_ => None
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}
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}
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}
|
|
|
|
/// An immutable representation of a row in a CSR matrix.
|
|
#[derive(Debug, Clone, PartialEq, Eq)]
|
|
pub struct CsrRow<'a, T> {
|
|
lane: CsLane<'a, T>
|
|
}
|
|
|
|
/// A mutable representation of a row in a CSR matrix.
|
|
///
|
|
/// Note that only explicitly stored entries can be mutated. The sparsity pattern belonging
|
|
/// to the row cannot be modified.
|
|
#[derive(Debug, PartialEq, Eq)]
|
|
pub struct CsrRowMut<'a, T> {
|
|
lane: CsLaneMut<'a, T>
|
|
}
|
|
|
|
/// Implement the methods common to both CsrRow and CsrRowMut
|
|
macro_rules! impl_csr_row_common_methods {
|
|
($name:ty) => {
|
|
impl<'a, T> $name {
|
|
/// The number of global columns in the row.
|
|
#[inline]
|
|
pub fn ncols(&self) -> usize {
|
|
self.lane.minor_dim()
|
|
}
|
|
|
|
/// The number of non-zeros in this row.
|
|
#[inline]
|
|
pub fn nnz(&self) -> usize {
|
|
self.lane.nnz()
|
|
}
|
|
|
|
/// The column indices corresponding to explicitly stored entries in this row.
|
|
#[inline]
|
|
pub fn col_indices(&self) -> &[usize] {
|
|
self.lane.minor_indices()
|
|
}
|
|
|
|
/// The values corresponding to explicitly stored entries in this row.
|
|
#[inline]
|
|
pub fn values(&self) -> &[T] {
|
|
self.lane.values()
|
|
}
|
|
|
|
/// Returns an entry for the given global column index.
|
|
///
|
|
/// Each call to this function incurs the cost of a binary search among the explicitly
|
|
/// stored column entries.
|
|
#[inline]
|
|
pub fn get_entry(&self, global_col_index: usize) -> Option<SparseEntry<T>> {
|
|
self.lane.get_entry(global_col_index)
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
impl_csr_row_common_methods!(CsrRow<'a, T>);
|
|
impl_csr_row_common_methods!(CsrRowMut<'a, T>);
|
|
|
|
impl<'a, T> CsrRowMut<'a, T> {
|
|
/// Mutable access to the values corresponding to explicitly stored entries in this row.
|
|
#[inline]
|
|
pub fn values_mut(&mut self) -> &mut [T] {
|
|
self.lane.values_mut()
|
|
}
|
|
|
|
/// Provides simultaneous access to column indices and mutable values corresponding to the
|
|
/// explicitly stored entries in this row.
|
|
///
|
|
/// This method primarily facilitates low-level access for methods that process data stored
|
|
/// in CSR format directly.
|
|
#[inline]
|
|
pub fn cols_and_values_mut(&mut self) -> (&[usize], &mut [T]) {
|
|
self.lane.indices_and_values_mut()
|
|
}
|
|
|
|
/// Returns a mutable entry for the given global column index.
|
|
#[inline]
|
|
pub fn get_entry_mut(&mut self, global_col_index: usize) -> Option<SparseEntryMut<T>> {
|
|
self.lane.get_entry_mut(global_col_index)
|
|
}
|
|
}
|
|
|
|
/// Row iterator for [CsrMatrix](struct.CsrMatrix.html).
|
|
pub struct CsrRowIter<'a, T> {
|
|
lane_iter: CsLaneIter<'a, T>
|
|
}
|
|
|
|
impl<'a, T> Iterator for CsrRowIter<'a, T> {
|
|
type Item = CsrRow<'a, T>;
|
|
|
|
fn next(&mut self) -> Option<Self::Item> {
|
|
self.lane_iter
|
|
.next()
|
|
.map(|lane| CsrRow { lane })
|
|
}
|
|
}
|
|
|
|
/// Mutable row iterator for [CsrMatrix](struct.CsrMatrix.html).
|
|
pub struct CsrRowIterMut<'a, T> {
|
|
lane_iter: CsLaneIterMut<'a, T>
|
|
}
|
|
|
|
impl<'a, T> Iterator for CsrRowIterMut<'a, T>
|
|
where
|
|
T: 'a
|
|
{
|
|
type Item = CsrRowMut<'a, T>;
|
|
|
|
fn next(&mut self) -> Option<Self::Item> {
|
|
self.lane_iter
|
|
.next()
|
|
.map(|lane| CsrRowMut { lane })
|
|
}
|
|
} |