Use initializing constructors in viterbi_decode and refactor size variables Q and T

Author: daschuer

lib/qm-dsp/dsp/tempotracking/TempoTrackV2.cpp

@@ -233,24 +233,19 @@ TempoTrackV2::viterbi_decode(const d_mat_t &rcfmat, const d_vec_t &wv, d_vec_t &
 {
     // following Kevin Murphy's Viterbi decoding to get best path of
     // beat periods through rfcmat
-    
-    int wv_len = int(wv.size());
-    
-    // make transition matrix
-    d_mat_t tmat;
-    for (int i = 0; i < wv_len; i++) {
-        tmat.push_back ( d_vec_t() ); // adds a new column
-        for (int j = 0; j < wv_len; j++) {
-            tmat[i].push_back(0.); // fill with zeros initially
-        }
-    }
 
+    if (rcfmat.size() < 2) return; // can't do anything at all meaningful
+
+    const std::size_t T = rcfmat.size();
+    const std::size_t Q = rcfmat[0].size();
+ 
+    auto tmat = d_mat_t(Q, d_vec_t(Q));
     // variance of Gaussians in transition matrix
     // formed of Gaussians on diagonal - implies slow tempo change
     double sigma = 8.;
     // don't want really short beat periods, or really long ones
-    for (int i = 20; i  < wv_len - 20; i++) {
-        for (int j = 20; j < wv_len - 20; j++) {
+    for (std::size_t i = 20; i  < Q - 20; i++) {
+        for (int j = 20; j < Q - 20; j++) {
             double mu = double(i);
             tmat[i][j] = exp( (-1.*pow((j-mu),2.)) / (2.*pow(sigma,2.)) );
         }
@@ -259,43 +254,28 @@ TempoTrackV2::viterbi_decode(const d_mat_t &rcfmat, const d_vec_t &wv, d_vec_t &
     // parameters for Viterbi decoding... this part is taken from
     // Murphy's matlab
 
-    d_mat_t delta;
-    i_mat_t psi;
-    for (int i = 0; i < int(rcfmat.size()); i++) {
-        delta.push_back(d_vec_t());
-        psi.push_back(i_vec_t());
-        for (int j = 0; j < int(rcfmat[i].size()); j++) {
-            delta[i].push_back(0.); // fill with zeros initially
-            psi[i].push_back(0); // fill with zeros initially
-        }
-    }
-
-    int T = int(delta.size());
-
-    if (T < 2) return; // can't do anything at all meaningful
-
-    int Q = int(delta[0].size());
+    auto delta = d_mat_t(T, d_vec_t(Q));
+    auto psi = i_mat_t(T, i_vec_t(Q));
 
     // initialize first column of delta
-    for (int j = 0; j < Q; j++) {
+    for (std::size_t j = 0; j < Q; j++) {
         delta[0][j] = wv[j] * rcfmat[0][j];
-        psi[0][j] = 0;
     }
 
     double deltasum = 0.;
-    for (int i = 0; i < Q; i++) {
+    for (std::size_t i = 0; i < Q; i++) {
         deltasum += delta[0][i];
     }
-    for (int i = 0; i < Q; i++) {
+    for (std::size_t i = 0; i < Q; i++) {
         delta[0][i] /= (deltasum + EPS);
     }
 
-    for (int t=1; t < T; t++)
+    for (std::size_t t=1; t < T; t++)
     {
         d_vec_t tmp_vec(Q);
 
-        for (int j = 0; j < Q; j++) {
-            for (int i = 0; i < Q; i++) {
+        for (std::size_t j = 0; j < Q; j++) {
+            for (std::size_t i = 0; i < Q; i++) {
                 tmp_vec[i] = delta[t-1][i] * tmat[j][i];
             }
 
@@ -308,10 +288,10 @@ TempoTrackV2::viterbi_decode(const d_mat_t &rcfmat, const d_vec_t &wv, d_vec_t &
 
         // normalise current delta column
         double deltasum = 0.;
-        for (int i = 0; i < Q; i++) {
+        for (std::size_t i = 0; i < Q; i++) {
             deltasum += delta[t][i];
         }
-        for (int i = 0; i < Q; i++) {
+        for (std::size_t i = 0; i < Q; i++) {
             delta[t][i] /= (deltasum + EPS);
         }
     }
@@ -329,7 +309,7 @@ TempoTrackV2::viterbi_decode(const d_mat_t &rcfmat, const d_vec_t &wv, d_vec_t &
     bestpath[0] = psi[1][bestpath[1]];
 
     for (std::size_t i = 0; i < beat_period.size(); i++) {
-        beat_period[i] = bestpath[i/128];
+        beat_period[i] = bestpath[i/Q];
         //        std::cerr << "bestpath[" << i << "] = " << bestpath[i] << " (used for beat_periods " << i*step << " to " << i*step+step-1 << ")" << std::endl;
     }
 }