From 2ddecee514736303cf998eba25d159551f8d7168 Mon Sep 17 00:00:00 2001
From: m5l14i11 <siarhei.melnik@proton.me>
Date: Wed, 5 Jul 2023 21:00:31 +0300
Subject: [PATCH] change

---
 ta_lib/utils/src/change.rs | 41 ++++++++++++++++++++++++++++++++++++++
 ta_lib/utils/src/lib.rs    |  1 +
 2 files changed, 42 insertions(+)
 create mode 100644 ta_lib/utils/src/change.rs

diff --git a/ta_lib/utils/src/change.rs b/ta_lib/utils/src/change.rs
new file mode 100644
index 00000000..cab544c7
--- /dev/null
+++ b/ta_lib/utils/src/change.rs
@@ -0,0 +1,41 @@
+pub fn change(source: &[f64], length: usize) -> Vec<f64> {
+    let len = source.len();
+    let mut change = vec![0.0; len];
+
+    if length > len {
+        return change;
+    }
+
+    for i in length..len {
+        change[i] = source[i] - source[i - length];
+    }
+
+    change
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_change() {
+        let source = vec![1.0, 2.0, 3.0, 4.0, 5.0];
+        let length = 2;
+        let expected = vec![0.0, 0.0, 2.0, 2.0, 2.0];
+
+        let result = change(&source, length);
+
+        assert_eq!(result, expected);
+    }
+
+    #[test]
+    fn test_change_zero_length() {
+        let source = vec![1.0, 2.0, 3.0, 4.0, 5.0];
+        let length = 0;
+        let expected = vec![0.0, 0.0, 0.0, 0.0, 0.0];
+
+        let result = change(&source, length);
+
+        assert_eq!(result, expected);
+    }
+}
diff --git a/ta_lib/utils/src/lib.rs b/ta_lib/utils/src/lib.rs
index 8f0b2cee..1924a882 100644
--- a/ta_lib/utils/src/lib.rs
+++ b/ta_lib/utils/src/lib.rs
@@ -1,3 +1,4 @@
+pub mod change;
 pub mod highest;
 pub mod lowest;
 pub mod nz;