From 0cecefcd9dba3194adf16bddcbf1ce4dfa3ac61d Mon Sep 17 00:00:00 2001
From: Mehmet Mert Yildiran <mehmetmertyildiran@gmail.com>
Date: Tue, 29 Oct 2019 04:26:15 +0300
Subject: [PATCH] Replace the random sampling function with C++17 equivalent

---
 .ale_config               |  1 +
 plexus/.ycm_extra_conf.py |  1 +
 plexus/network.hpp        | 27 ++++++++++++++-------------
 plexus/plexus.cpp         | 15 +++++++++------
 setup.py                  |  2 +-
 5 files changed, 26 insertions(+), 20 deletions(-)

diff --git a/.ale_config b/.ale_config
index 64b74fa..13b2bf0 100644
--- a/.ale_config
+++ b/.ale_config
@@ -13,3 +13,4 @@
 -fPIC
 -I/usr/include/python3.6m
 -w
+-std=c++17
diff --git a/plexus/.ycm_extra_conf.py b/plexus/.ycm_extra_conf.py
index 1d1eb58..fac5cac 100644
--- a/plexus/.ycm_extra_conf.py
+++ b/plexus/.ycm_extra_conf.py
@@ -16,5 +16,6 @@ def Settings(**kwargs):
             '-fPIC',
             '-I/usr/include/python3.6m',
             '-w',
+            '-std=c++17',
         ],
     }
diff --git a/plexus/network.hpp b/plexus/network.hpp
index 8cfd0f6..7293917 100644
--- a/plexus/network.hpp
+++ b/plexus/network.hpp
@@ -5,6 +5,8 @@
 #include <thread>
 #include <vector>
 #include <unordered_map>
+#include <random>
+#include <algorithm>
 
 class Neuron;
 
@@ -81,17 +83,16 @@ class Network
     void load(std::vector<double> input_arr, std::vector<double> output_arr);
 };
 
-// Function to get a random sampling from a vector
-// using Fisher-Yates shuffle method
-template<class BidiIter >
-BidiIter random_unique(BidiIter begin, BidiIter end, size_t num_random) {
-    size_t left = std::distance(begin, end);
-    while (num_random--) {
-        BidiIter r = begin;
-        std::advance(r, rand()%left);
-        std::swap(*begin, *r);
-        ++begin;
-        --left;
-    }
-    return begin;
+
+// Requires -std=c++17 compilation flag
+template<class RandomSampling>
+RandomSampling random_sample(
+    RandomSampling neurons,
+    unsigned int sample_length
+)
+{
+    RandomSampling sample;
+    std::sample(neurons.begin(), neurons.end(), std::back_inserter(sample),
+        sample_length, std::mt19937{std::random_device{}()});
+    return sample;
 }
diff --git a/plexus/plexus.cpp b/plexus/plexus.cpp
index 6daf7e1..07e73a9 100644
--- a/plexus/plexus.cpp
+++ b/plexus/plexus.cpp
@@ -23,7 +23,8 @@ Neuron::Neuron(Network& network)
 void Neuron::partially_subscribe()
 {
     if (this->subscriptions.size() == 0) {
-        unsigned seed = std::chrono::system_clock::now().time_since_epoch().count();
+        unsigned seed = std::chrono::system_clock::now()
+            .time_since_epoch().count();
         std::default_random_engine generator (seed);
         std::normal_distribution<double> distribution(
             this->network->get_connectivity(),
@@ -34,9 +35,12 @@ void Neuron::partially_subscribe()
             sample_length = this->network->nonmotor_neurons.size();
         if (sample_length <= 0)
             sample_length = 0;
+        std::vector<Neuron*> elected = random_sample(
+            this->network->nonmotor_neurons,
+            sample_length
+        );
         this->subscriptions.reserve(sample_length);
-        for (unsigned int i = 0; i < sample_length; i++) {
-            Neuron* target_neuron = this->network->nonmotor_neurons[i];
+        for (auto target_neuron: elected) {
             if (target_neuron != this) {
                 this->subscriptions.insert(
                     std::pair<Neuron*, double>(
@@ -203,9 +207,8 @@ void Network::_ignite(Network* network)
     std::vector<Neuron*> ban_list;
     while (network->freezer == false) {
         if (network->randomly_fire) {
-            Neuron* neuron = random_unique(
-                network->nonsensory_neurons.begin(),
-                network->nonsensory_neurons.end(),
+            Neuron* neuron = random_sample(
+                network->nonsensory_neurons,
                 1
             )[0];
             if (neuron->type == MOTOR_NEURON) {
diff --git a/setup.py b/setup.py
index 46da1b7..c14f835 100644
--- a/setup.py
+++ b/setup.py
@@ -102,7 +102,7 @@
             name='cplexus',
             sources=['plexus/plexus.cpp', 'plexus/wrapper.cpp'],
             language='c++',
-            extra_compile_args=['-w'],
+            extra_compile_args=['-w', '-std=c++17'],
         )
     ]
 )