From 12740038720aa62cd25a12fd6bedc4f38b4eb2f2 Mon Sep 17 00:00:00 2001
From: xd009642 <danielmckenna93@gmail.com>
Date: Tue, 26 Feb 2019 21:43:45 +0000
Subject: [PATCH 1/3] Added a cumulative sum function to Histogram

This is equivalent to the cumsum for numpys histogram object.
---
 src/histogram/histograms.rs | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/src/histogram/histograms.rs b/src/histogram/histograms.rs
index 825aadb7..888b573a 100644
--- a/src/histogram/histograms.rs
+++ b/src/histogram/histograms.rs
@@ -78,6 +78,16 @@ impl<A: Ord> Histogram<A> {
     pub fn grid(&self) -> &Grid<A> {
         &self.grid
     }
+
+    /// Returns the cumulative distribution function of a histogram. 
+    /// Equivalent to the numpy histogram function cumsum
+    pub fn cumulative_sum(&self) -> ArrayD<usize> {
+        let mut total = 0;
+        self.counts.mapv(|x| {
+            total += x;
+            total
+        })
+    }
 }
 
 /// Extension trait for `ArrayBase` providing methods to compute histograms.
@@ -163,3 +173,23 @@ impl<A, S> HistogramExt<A, S> for ArrayBase<S, Ix2>
         histogram
     }
 }
+
+#[cfg(test)]
+mod auto_tests {
+    use super::*;
+    use histogram::histograms::HistogramExt;
+    use histogram::bins::{Bins, Edges};
+
+    #[test]
+    fn histogram_cdf() {
+        let data = arr2(&[[1], [2], [3], [4], [1], [1], [4], [5], [8], [8], [8]]);
+        let grid = Grid::from(vec![
+                              Bins::new(
+                                  Edges::from(vec![0,1,2,3,4,5,6,7,8,9]))]);
+
+        let histogram = data.histogram(grid);
+                       //0, 1  2  3  4  5  6  7  8
+        let cdf = arr1(&[0, 3, 4, 5, 7, 8, 8, 8, 11]).into_dyn();
+        assert_eq!(histogram.cumulative_sum(), cdf);
+    }
+}

From cd17003e1ca8696aa7122765622a820dc6342032 Mon Sep 17 00:00:00 2001
From: xd009642 <danielmckenna93@gmail.com>
Date: Wed, 27 Feb 2019 22:23:14 +0000
Subject: [PATCH 2/3] Made CDF n-dimensional

---
 src/histogram/histograms.rs | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/histogram/histograms.rs b/src/histogram/histograms.rs
index 888b573a..38f8f420 100644
--- a/src/histogram/histograms.rs
+++ b/src/histogram/histograms.rs
@@ -82,11 +82,15 @@ impl<A: Ord> Histogram<A> {
     /// Returns the cumulative distribution function of a histogram. 
     /// Equivalent to the numpy histogram function cumsum
     pub fn cumulative_sum(&self) -> ArrayD<usize> {
-        let mut total = 0;
-        self.counts.mapv(|x| {
-            total += x;
-            total
-        })
+        let mut cdf = self.counts.clone();
+        for i in 0..self.ndim() {
+            for j in 1..cdf.shape()[i] { 
+                let temp = cdf.index_axis(Axis(i), j - 1).to_owned();
+                let mut ax = cdf.index_axis_mut(Axis(i), j);
+                ax += &temp;
+            }
+        }
+        cdf
     }
 }
 

From 6e84659befdc0815c965ac4891343500b1ee521d Mon Sep 17 00:00:00 2001
From: xd009642 <danielmckenna93@gmail.com>
Date: Thu, 28 Feb 2019 17:51:26 +0000
Subject: [PATCH 3/3] Added 2D CDF test for histogram

---
 src/histogram/histograms.rs | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/histogram/histograms.rs b/src/histogram/histograms.rs
index 38f8f420..0a0529cd 100644
--- a/src/histogram/histograms.rs
+++ b/src/histogram/histograms.rs
@@ -185,7 +185,7 @@ mod auto_tests {
     use histogram::bins::{Bins, Edges};
 
     #[test]
-    fn histogram_cdf() {
+    fn histogram_cdf_1d() {
         let data = arr2(&[[1], [2], [3], [4], [1], [1], [4], [5], [8], [8], [8]]);
         let grid = Grid::from(vec![
                               Bins::new(
@@ -196,4 +196,20 @@ mod auto_tests {
         let cdf = arr1(&[0, 3, 4, 5, 7, 8, 8, 8, 11]).into_dyn();
         assert_eq!(histogram.cumulative_sum(), cdf);
     }
+    
+    #[test]
+    fn histogram_cdf_2d() {
+        let data = arr2(&[[0, 2], [4, 4], [1, 1], [3, 3], [0, 2]]);
+        let grid = Grid::from(vec![
+                              Bins::new(Edges::from(vec![0, 1, 2, 3, 4])),
+                              Bins::new(Edges::from(vec![0, 1, 2, 3, 4]))]);
+
+        let histogram = data.histogram(grid);
+
+        let cdf = arr2(&[[0, 0, 2, 2],
+                         [0, 1, 3, 3],
+                         [0, 1, 3, 3],
+                         [0, 1, 3, 4]]).into_dyn();
+        assert_eq!(histogram.cumulative_sum(), cdf);
+    }
 }