From b36f56a6dbf6006712f5ba6978626106df6a11b0 Mon Sep 17 00:00:00 2001
From: Michael Neumann <mneumann@ntecs.de>
Date: Thu, 11 Apr 2019 00:13:35 +0200
Subject: [PATCH 1/2] Implement Zip::all()

Test if every element of the iterator matches a predicate.

This is useful, for instance, to test if two matrices are elementwise
"similar" (within a given threshold) without modifying the matrices.
---
 src/zip/mod.rs | 16 ++++++++++++++++
 tests/azip.rs  | 16 ++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/src/zip/mod.rs b/src/zip/mod.rs
index b26e2aebb..5492505c0 100644
--- a/src/zip/mod.rs
+++ b/src/zip/mod.rs
@@ -738,6 +738,22 @@ macro_rules! map_impl {
                 })
             }
 
+            /// Tests if every element of the iterator matches a predicate.
+            ///
+            /// Returns `true` if `predicate` evaluates to `true` for all elements.
+            pub fn all<F>(mut self, mut predicate: F) -> bool
+                where F: FnMut($($p::Item),*) -> bool
+            {
+                self.apply_core(true, move |_, args| {
+                    let ($($p,)*) = args;
+                    if predicate($($p),*) {
+                        FoldWhile::Continue(true)
+                    } else {
+                        FoldWhile::Done(false)
+                    }
+                }).into_inner()
+            }
+
             expand_if!(@bool [$notlast]
 
             /// Include the producer `p` in the Zip.
diff --git a/tests/azip.rs b/tests/azip.rs
index a5e53e0e0..3364f3c67 100644
--- a/tests/azip.rs
+++ b/tests/azip.rs
@@ -271,3 +271,19 @@ fn test_indices_split_1() {
         }
     }
 }
+
+#[test]
+fn test_zip_all() {
+    let a = Array::<f32, _>::zeros(62);
+    let b = Array::<f32, _>::ones(62);
+    assert_eq!(true, Zip::from(&a).and(&b).all(|&x, &y| x + y == 1.0));
+    assert_eq!(false, Zip::from(&a).and(&b).all(|&x, &y| x == y));
+}
+
+#[test]
+fn test_zip_all_empty_array() {
+    let a = Array::<f32, _>::zeros(0);
+    let b = Array::<f32, _>::ones(0);
+    assert_eq!(true, Zip::from(&a).and(&b).all(|&_x, &_y| true));
+    assert_eq!(true, Zip::from(&a).and(&b).all(|&_x, &_y| false));
+}

From 48275c40655d37bfb9cac48b75b99e9648a55e67 Mon Sep 17 00:00:00 2001
From: Michael Neumann <mneumann@ntecs.de>
Date: Sat, 13 Apr 2019 16:17:36 +0200
Subject: [PATCH 2/2] Enhance documentation and test cases for Zip::all()

---
 src/zip/mod.rs | 10 ++++++++++
 tests/azip.rs  |  3 +++
 2 files changed, 13 insertions(+)

diff --git a/src/zip/mod.rs b/src/zip/mod.rs
index 5492505c0..fc8b99c7d 100644
--- a/src/zip/mod.rs
+++ b/src/zip/mod.rs
@@ -741,6 +741,16 @@ macro_rules! map_impl {
             /// Tests if every element of the iterator matches a predicate.
             ///
             /// Returns `true` if `predicate` evaluates to `true` for all elements.
+            /// Returns `true` if the input arrays are empty.
+            ///
+            /// Example:
+            ///
+            /// ```
+            /// use ndarray::{array, Zip};
+            /// let a = array![1, 2, 3];
+            /// let b = array![1, 4, 9];
+            /// assert!(Zip::from(&a).and(&b).all(|&a, &b| a * a == b));
+            /// ```
             pub fn all<F>(mut self, mut predicate: F) -> bool
                 where F: FnMut($($p::Item),*) -> bool
             {
diff --git a/tests/azip.rs b/tests/azip.rs
index 3364f3c67..39a5d2991 100644
--- a/tests/azip.rs
+++ b/tests/azip.rs
@@ -276,8 +276,11 @@ fn test_indices_split_1() {
 fn test_zip_all() {
     let a = Array::<f32, _>::zeros(62);
     let b = Array::<f32, _>::ones(62);
+    let mut c = Array::<f32, _>::ones(62);
+    c[5] = 0.0;
     assert_eq!(true, Zip::from(&a).and(&b).all(|&x, &y| x + y == 1.0));
     assert_eq!(false, Zip::from(&a).and(&b).all(|&x, &y| x == y));
+    assert_eq!(false, Zip::from(&a).and(&c).all(|&x, &y| x + y == 1.0));
 }
 
 #[test]