From ad4fbabeca2cbdf4cb47f1a923183027494ab0a8 Mon Sep 17 00:00:00 2001
From: Samuel Fadel <samuelfadel@gmail.com>
Date: Thu, 22 Oct 2015 16:39:15 -0200
Subject: Added PLMP as an alternative technique to use; knn() is now exposed
 in the mp namespace.

---
 main.cpp | 104 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 92 insertions(+), 12 deletions(-)

(limited to 'main.cpp')

diff --git a/main.cpp b/main.cpp
index 8355590..4aad1db 100644
--- a/main.cpp
+++ b/main.cpp
@@ -27,6 +27,69 @@ static QObject *mainProvider(QQmlEngine *engine, QJSEngine *scriptEngine)
     return Main::instance();
 }
 
+static inline double hBeta(const arma::rowvec &Di, double beta, arma::rowvec &Pi) {
+    Pi = arma::exp(-Di * beta);
+    double sumPi = arma::accu(Pi);
+    double h = log(sumPi) + beta * arma::accu(Di % Pi) / sumPi;
+    Pi /= sumPi;
+    return h;
+}
+
+static void calcP(const arma::mat &X, arma::mat &P, double perplexity = 30, double tol = 1e-5) {
+    arma::colvec sumX = arma::sum(X % X, 1);
+    arma::mat D = -2 * (X * X.t());
+    D.each_col() += sumX;
+    arma::inplace_trans(D);
+    D.each_col() += sumX;
+    D.diag() *= 0;
+    double logU = log(perplexity);
+    arma::rowvec beta(X.n_rows, arma::fill::ones);
+
+    arma::rowvec Pi(X.n_rows);
+    for (arma::uword i = 0; i < X.n_rows; i++) {
+        double betaMin = -arma::datum::inf;
+        double betaMax =  arma::datum::inf;
+        arma::rowvec Di = D.row(i);
+        double h = hBeta(Di, beta[i], Pi);
+
+        double hDiff = h - logU;
+        for (int tries = 0; fabs(hDiff) > tol && tries < 50; tries++) {
+            if (hDiff > 0) {
+                betaMin = beta[i];
+                if (betaMax == arma::datum::inf || betaMax == -arma::datum::inf) {
+                    beta[i] *= 2;
+                } else {
+                    beta[i] = (beta[i] + betaMax) / 2.;
+                }
+            } else {
+                betaMax = beta[i];
+                if (betaMin == arma::datum::inf || betaMin == -arma::datum::inf) {
+                    beta[i] /= 2;
+                } else {
+                    beta[i] = (beta[i] + betaMin) / 2.;
+                }
+            }
+
+            h = hBeta(Di, beta[i], Pi);
+            hDiff = h - logU;
+        }
+
+        P.row(i) = Pi;
+    }
+}
+
+arma::uvec relevanceSampling(const arma::mat &X, int subsampleSize)
+{
+    arma::mat P(X.n_rows, X.n_rows);
+    calcP(X, P);
+    P = (P + P.t());
+    P /= arma::accu(P);
+    P.transform([](double p) { return std::max(p, 1e-12); });
+
+    arma::uvec indices = arma::sort_index(arma::sum(P));
+    return indices(arma::span(0, subsampleSize - 1));
+}
+
 int main(int argc, char **argv)
 {
     QApplication app(argc, argv);
@@ -55,24 +118,40 @@ int main(int argc, char **argv)
     }
 
     Main *m = Main::instance();
-    if (parser.isSet(indicesFileOutputOption)) {
-        m->setIndicesSavePath(parser.value(indicesFileOutputOption));
-    }
-    if (parser.isSet(subsampleFileOutputOption)) {
-        m->setSubsampleSavePath(parser.value(subsampleFileOutputOption));
-    }
     m->loadDataset(args[0].toStdString());
-
     arma::mat X = m->X();
     arma::vec labels = m->labels();
 
     arma::uword n = X.n_rows;
-    arma::uword subsampleSize = (arma::uword) n / 10.f;
-    arma::uvec sampleIndices = arma::randi<arma::uvec>(subsampleSize, arma::distr_param(0, n-1));
-    m->setSubsampleIndices(sampleIndices);
+    int subsampleSize = 3 * ((int) sqrt(n));
+    arma::uvec sampleIndices;
+    arma::mat Ys;
+
+    if (parser.isSet(indicesFileOutputOption)) {
+        const QString &indicesFilename = parser.value(indicesFileOutputOption);
+        m->setIndicesSavePath(indicesFilename);
+        QFile indicesFile(indicesFilename);
+        if (indicesFile.exists()) {
+            sampleIndices.load(indicesFilename.toStdString(), arma::raw_ascii);
+            subsampleSize = sampleIndices.n_elem;
+        } else {
+            sampleIndices = relevanceSampling(X, subsampleSize);
+        }
+    }
+    if (parser.isSet(subsampleFileOutputOption)) {
+        const QString &subsampleFilename = parser.value(subsampleFileOutputOption);
+        m->setSubsampleSavePath(subsampleFilename);
+        QFile subsampleFile(subsampleFilename);
+        if (subsampleFile.exists()) {
+            Ys.load(subsampleFilename.toStdString(), arma::raw_ascii);
+        } else {
+            Ys.set_size(subsampleSize, 2);
+            mp::forceScheme(mp::dist(X.rows(sampleIndices)), Ys);
+        }
+    }
 
-    arma::mat Ys(subsampleSize, 2, arma::fill::randn);
-    mp::forceScheme(mp::dist(X.rows(sampleIndices)), Ys);
+    m->setSubsampleIndices(sampleIndices);
+    m->setSubsample(Ys);
 
     qmlRegisterType<Scatterplot>("PM", 1, 0, "Scatterplot");
     qmlRegisterType<HistoryGraph>("PM", 1, 0, "HistoryGraph");
@@ -113,6 +192,7 @@ int main(int argc, char **argv)
 
     // Update LAMP projection as the subsample is modified
     InteractionHandler interactionHandler(X, sampleIndices);
+    interactionHandler.setTechnique(InteractionHandler::TECHNIQUE_LAMP);
     QObject::connect(subsamplePlot, SIGNAL(xyChanged(const arma::mat &)),
             &interactionHandler, SLOT(setSubsample(const arma::mat &)));
     QObject::connect(subsamplePlot, SIGNAL(xyInteractivelyChanged(const arma::mat &)),
-- 
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