From 17c12bbd1b2fdfc958f12527538acb787cc2d89a Mon Sep 17 00:00:00 2001
From: Mihnea Dobrescu-Balaur <mihnea@linux.com>
Date: Wed, 7 Aug 2013 09:46:09 -0700
Subject: [PATCH] Add frequency count to extra::stat. #8281

---
 src/libextra/stats.rs | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/libextra/stats.rs b/src/libextra/stats.rs
index 68d5af43688..9238034cba3 100644
--- a/src/libextra/stats.rs
+++ b/src/libextra/stats.rs
@@ -10,6 +10,7 @@
 
 use sort;
 use std::cmp;
+use std::hashmap;
 use std::io;
 use std::num;
 
@@ -352,6 +353,16 @@ pub fn write_boxplot(w: @io::Writer, s: &Summary, width_hint: uint) {
     w.write_str(histr);
 }
 
+/// Returns a HashMap with the number of occurences of every element in the
+/// sequence that the iterator exposes.
+pub fn freq_count<T: Iterator<U>, U: Eq+Hash>(mut iter: T) -> hashmap::HashMap<U, uint> {
+    let mut map = hashmap::HashMap::new::<U, uint>();
+    for elem in iter {
+        map.insert_or_update_with(elem, 1, |_, count| *count += 1);
+    }
+    map
+}
+
 // Test vectors generated from R, using the script src/etc/stat-test-vectors.r.
 
 #[cfg(test)]
-- 
2.44.0