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sparse: fix alist format by including padding #3

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Oct 4, 2024
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sparse: fix alist format by including padding #3

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30 changes: 15 additions & 15 deletions src/mackay_neal.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -283,21 +283,21 @@ mod tests {
};
let h = conf.run(187).unwrap();
let alist = "8 4
2 4
2 2 2 2 2 2 2 2
4 4 4 4
1 3
3 4
1 4
1 4
1 2
2 3
2 3
2 4
1 3 4 5
5 6 7 8
1 2 6 7
2 3 4 8
2 4
2 2 2 2 2 2 2 2
4 4 4 4
1 3
3 4
1 4
1 4
1 2
2 3
2 3
2 4
1 3 4 5
5 6 7 8
1 2 6 7
2 3 4 8
";
assert_eq!(h.alist(), alist);
}
Expand Down
200 changes: 164 additions & 36 deletions src/sparse.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -226,45 +226,104 @@ impl SparseMatrix {
self.cols[col].iter()
}

/// Writes the matrix in alist format to a writer
///
/// # Errors
/// If a call to `write!()` returns an error, this function returns
/// such an error.
pub fn write_alist<W: std::fmt::Write>(&self, w: &mut W) -> std::fmt::Result {
fn write_alist_maybe_padding<W: std::fmt::Write>(
&self,
w: &mut W,
use_padding: bool,
) -> std::fmt::Result {
writeln!(w, "{} {}", self.num_cols(), self.num_rows())?;
let directions = [&self.cols, &self.rows];
for dir in directions.iter() {
write!(w, "{} ", dir.iter().map(|el| el.len()).max().unwrap_or(0))?;
let mut direction_lengths = [0, 0];
for (dir, len) in directions.iter().zip(direction_lengths.iter_mut()) {
*len = dir.iter().map(|el| el.len()).max().unwrap_or(0);
}
writeln!(w)?;
writeln!(w, "{} {}", direction_lengths[0], direction_lengths[1])?;
for dir in directions.iter() {
for el in *dir {
write!(w, "{} ", el.len())?;
let mut lengths = dir.iter().map(|el| el.len());
if let Some(len) = lengths.next() {
write!(w, "{}", len)?;
}
for len in lengths {
write!(w, " {}", len)?;
}
writeln!(w)?;
}
for dir in directions.iter() {
for (dir, &dirlen) in directions.iter().zip(direction_lengths.iter()) {
for el in *dir {
let mut v = el.clone();
v.sort_unstable();
for x in &v {
write!(w, "{} ", x + 1)?;
let vlen = v.len();
let mut v = v.iter().map(|x| x + 1);
if let Some(x) = v.next() {
write!(w, "{}", x)?;
}
for x in v {
write!(w, " {}", x)?;
}
if use_padding {
if vlen == 0 {
write!(w, "0")?;
}
// .max(1) because we've added one padding element if vlen
// was zero
let num_padding = dirlen - vlen.max(1);
for _ in 0..num_padding {
write!(w, " 0")?;
}
}
writeln!(w)?;
}
}
Ok(())
}

/// Returns a [`String`] with the alist representation of the matrix
/// Writes the matrix in alist format to a writer.
///
/// This function includes zeros as padding for irregular codes, as
/// originally defined by MacKay.
///
/// # Errors
/// If a call to `write!()` returns an error, this function returns
/// such an error.
pub fn write_alist<W: std::fmt::Write>(&self, w: &mut W) -> std::fmt::Result {
self.write_alist_maybe_padding(w, true)
}

/// Writes the matrix in alist format to a writer.
///
/// This function does not include zeros as padding for irregular codes.
///
/// # Errors
/// If a call to `write!()` returns an error, this function returns
/// such an error.
pub fn write_alist_no_padding<W: std::fmt::Write>(&self, w: &mut W) -> std::fmt::Result {
self.write_alist_maybe_padding(w, false)
}

/// Returns a [`String`] with the alist representation of the matrix.
///
/// This function includes zeros as padding for irregular codes, as
/// originally defined by MacKay.
pub fn alist(&self) -> String {
let mut s = String::new();
self.write_alist(&mut s).unwrap();
s
}

/// Constructs and returns a sparse matrix from its alist representation
/// Returns a [`String`] with the alist representation of the matrix.
///
/// This function does not include zeros as padding for irregular codes.
pub fn alist_no_padding(&self) -> String {
let mut s = String::new();
self.write_alist_no_padding(&mut s).unwrap();
s
}

/// Constructs and returns a sparse matrix from its alist representation.
///
/// This function is able to read alists that use zeros for padding in the
/// case of an irregular code (as was defined originally by MacKay), as well
/// as alists that omit these zeros.
///
/// # Errors
/// `alist` should hold a valid alist representation. If an error is found
Expand Down Expand Up @@ -298,7 +357,10 @@ impl SparseMatrix {
let row: usize = row
.parse()
.map_err(|_| String::from("row value is not a number"))?;
h.insert(row - 1, col);
// row == 0 is used for padding in irregular codes
if row != 0 {
h.insert(row - 1, col);
}
}
}
// we do not need to process the rows of the alist
Expand Down Expand Up @@ -471,29 +533,95 @@ mod tests {
h.insert(j, j + 8);
}
let expected = "12 4
1 3
1 1 1 1 1 1 1 1 1 1 1 1
3 3 3 3
1
2
3
4
1
2
3
4
1
2
3
4
1 5 9
2 6 10
3 7 11
4 8 12
1 3
1 1 1 1 1 1 1 1 1 1 1 1
3 3 3 3
1
2
3
4
1
2
3
4
1
2
3
4
1 5 9
2 6 10
3 7 11
4 8 12
";
assert_eq!(h.alist(), expected);

let h2 = SparseMatrix::from_alist(expected).unwrap();
assert_eq!(h2.alist(), expected);
}

#[test]
fn test_alist_irregular() {
let mut h = SparseMatrix::new(4, 12);
for j in 0..4 {
h.insert(j, j);
h.insert(j, j + 4);
if j < 2 {
h.insert(j, j + 8);
}
}

// with zero padding

let expected = "12 4
1 3
1 1 1 1 1 1 1 1 1 1 0 0
3 3 2 2
1
2
3
4
1
2
3
4
1
2
0
0
1 5 9
2 6 10
3 7 0
4 8 0
";
let expected_no_padding = "12 4
1 3
1 1 1 1 1 1 1 1 1 1 0 0
3 3 2 2
1
2
3
4
1
2
3
4
1
2


1 5 9
2 6 10
3 7
4 8
";

assert_eq!(h.alist(), expected);
assert_eq!(h.alist_no_padding(), expected_no_padding);
let h2 = SparseMatrix::from_alist(expected).unwrap();
assert_eq!(h2.alist(), expected);
assert_eq!(h2.alist_no_padding(), expected_no_padding);
let h3 = SparseMatrix::from_alist(expected_no_padding).unwrap();
assert_eq!(h3.alist(), expected);
assert_eq!(h3.alist_no_padding(), expected_no_padding);
}
}
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