From 60a7ae725aa3e4802489a8cafaba87e860da737b Mon Sep 17 00:00:00 2001
From: erius <egor_kapralov2003@mail.ru>
Date: Sat, 18 May 2024 16:16:14 +0300
Subject: [PATCH] ColumnIter

---
 src/math/matrix/iter.rs | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/src/math/matrix/iter.rs b/src/math/matrix/iter.rs
index 079eff7..6bbcc97 100644
--- a/src/math/matrix/iter.rs
+++ b/src/math/matrix/iter.rs
@@ -31,8 +31,8 @@ impl<T: Num + Clone> Matrix<T> {
         self.data.chunks(self.width)
     }
 
-    pub fn iter_column(&self) -> () {
-        todo!()
+    pub fn iter_column(&self, j: usize) -> ColumnIter<T> {
+        ColumnIter { row_start: 0, column_index: j, matrix: self }
     }
 
     pub fn iter_columns(&self) -> () {
@@ -62,6 +62,10 @@ pub struct IterIndexedMut<'a, T: Num> {
     matrix_iter_mut: std::slice::IterMut<'a, T>
 }
 
+pub struct ColumnIter<'a, T: Num> {
+    row_start: usize, column_index: usize, matrix: &'a Matrix<T>
+}
+
 pub struct IterIndices {
     i: usize, j: usize, width: usize, height: usize
 }
@@ -84,6 +88,17 @@ impl<'a, T: Num> Iterator for IterIndexedMut<'a, T> {
     }
 }
 
+impl<'a, T: Num> Iterator for ColumnIter<'a, T> {
+    type Item = &'a T;
+    fn next(&mut self) -> Option<Self::Item> {
+        let elem_index = self.row_start + self.column_index;
+        if elem_index >= self.matrix.data.len() { return None; }
+        let elem = &self.matrix.data[elem_index];
+        self.row_start += self.matrix.width;
+        Some(elem)
+    }
+}
+
 impl Iterator for IterIndices {
     type Item = (usize, usize);
     fn next(&mut self) -> Option<Self::Item> {