From a72bb7542b69d5b15143f7759e96818ea5d52e08 Mon Sep 17 00:00:00 2001
From: Bert Peters <bert@bertptrs.nl>
Date: Tue, 27 Mar 2018 15:20:53 +0200
Subject: [PATCH] Break after reaching small interactions. Refs #5.

---
 src/fmri/utils.hpp          |  6 ++++--
 src/fmri/visualisations.cpp | 10 +++++++---
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/fmri/utils.hpp b/src/fmri/utils.hpp
index 95cabf3..07ed1e2 100644
--- a/src/fmri/utils.hpp
+++ b/src/fmri/utils.hpp
@@ -21,6 +21,8 @@ namespace fmri
      */
 	extern const float LAYER_X_OFFSET;
 
+    constexpr const float EPSILON = 1e-10f;
+
     /**
      * Identity function that simply returns whatever is put in.
      *
@@ -193,7 +195,7 @@ namespace fmri
      * @return A vector of the indices before the partitioning cut-off.
      */
     template<class Iter, class Compare>
-    std::vector<std::size_t> arg_nth_element(Iter first, Iter middle, Iter last, Compare compare)
+    std::vector<std::size_t> arg_partial_sort(Iter first, Iter middle, Iter last, Compare compare)
     {
         using namespace std;
 
@@ -203,7 +205,7 @@ namespace fmri
         vector<size_t> indices(total);
         iota(indices.begin(), indices.end(), 0u);
 
-        nth_element(indices.begin(), indices.begin() + n, indices.end(), [=](size_t a, size_t b) {
+        partial_sort(indices.begin(), indices.begin() + n, indices.end(), [=](size_t a, size_t b) {
             return compare(*(first + a), *(first + b));
         });
 
diff --git a/src/fmri/visualisations.cpp b/src/fmri/visualisations.cpp
index 65d18f6..a56aff6 100644
--- a/src/fmri/visualisations.cpp
+++ b/src/fmri/visualisations.cpp
@@ -113,14 +113,18 @@ static Animation *getFullyConnectedAnimation(const fmri::LayerData &prevState, c
     }
 
     const auto desiredSize = min(INTERACTION_LIMIT, numEntries);
-    auto idx = arg_nth_element(interactions.begin(), interactions.begin() + desiredSize, interactions.end(), [](auto a, auto b) {
-        return abs(a) > abs(b);
-    });
+    auto idx = arg_partial_sort(interactions.begin(), interactions.begin() + desiredSize, interactions.end(),
+                                [](auto a, auto b) {
+                                    return abs(a) > abs(b);
+                                });
 
     EntryList result;
     result.reserve(desiredSize);
     const auto normalizer = getNodeNormalizer(prevState);
     for (auto i : idx) {
+        if (abs(interactions[i]) < EPSILON){
+            break;
+        }
         result.emplace_back(interactions[i], make_pair((i % shape[1]) / normalizer, i / shape[1]));
     }