nalgebra/src/sparse/cs_matrix_conversion.rs

115 lines
3.1 KiB
Rust

use alga::general::ClosedAdd;
use num::Zero;
use crate::allocator::Allocator;
use crate::sparse::cs_utils;
use crate::sparse::{CsMatrix, CsStorage};
use crate::storage::Storage;
use crate::{DefaultAllocator, Dim, Dynamic, Matrix, MatrixMN, Scalar};
impl<'a, N: Scalar + Zero + ClosedAdd> CsMatrix<N> {
/// Creates a column-compressed sparse matrix from a sparse matrix in triplet form.
pub fn from_triplet(
nrows: usize,
ncols: usize,
irows: &[usize],
icols: &[usize],
vals: &[N],
) -> Self
{
Self::from_triplet_generic(Dynamic::new(nrows), Dynamic::new(ncols), irows, icols, vals)
}
}
impl<'a, N: Scalar + Zero + ClosedAdd, R: Dim, C: Dim> CsMatrix<N, R, C>
where DefaultAllocator: Allocator<usize, C> + Allocator<N, R>
{
/// Creates a column-compressed sparse matrix from a sparse matrix in triplet form.
pub fn from_triplet_generic(
nrows: R,
ncols: C,
irows: &[usize],
icols: &[usize],
vals: &[N],
) -> Self
{
assert!(vals.len() == irows.len());
assert!(vals.len() == icols.len());
let mut res = CsMatrix::new_uninitialized_generic(nrows, ncols, vals.len());
let mut workspace = res.data.p.clone();
// Column count.
for j in icols.iter().cloned() {
workspace[j] += 1;
}
let _ = cs_utils::cumsum(&mut workspace, &mut res.data.p);
// Fill i and vals.
for ((i, j), val) in irows
.iter()
.cloned()
.zip(icols.iter().cloned())
.zip(vals.iter().cloned())
{
let offset = workspace[j];
res.data.i[offset] = i;
res.data.vals[offset] = val;
workspace[j] = offset + 1;
}
// Sort the result.
res.sort();
res.dedup();
res
}
}
impl<'a, N: Scalar + Zero, R: Dim, C: Dim, S> From<CsMatrix<N, R, C, S>> for MatrixMN<N, R, C>
where
S: CsStorage<N, R, C>,
DefaultAllocator: Allocator<N, R, C>,
{
fn from(m: CsMatrix<N, R, C, S>) -> Self {
let (nrows, ncols) = m.data.shape();
let mut res = MatrixMN::zeros_generic(nrows, ncols);
for j in 0..ncols.value() {
for (i, val) in m.data.column_entries(j) {
res[(i, j)] = val;
}
}
res
}
}
impl<'a, N: Scalar + Zero, R: Dim, C: Dim, S> From<Matrix<N, R, C, S>> for CsMatrix<N, R, C>
where
S: Storage<N, R, C>,
DefaultAllocator: Allocator<N, R, C> + Allocator<usize, C>,
{
fn from(m: Matrix<N, R, C, S>) -> Self {
let (nrows, ncols) = m.data.shape();
let len = m.iter().filter(|e| !e.is_zero()).count();
let mut res = CsMatrix::new_uninitialized_generic(nrows, ncols, len);
let mut nz = 0;
for j in 0..ncols.value() {
let column = m.column(j);
res.data.p[j] = nz;
for i in 0..nrows.value() {
if !column[i].is_zero() {
res.data.i[nz] = i;
res.data.vals[nz] = column[i];
nz += 1;
}
}
}
res
}
}