diff --git a/src/snapshot.cpp b/src/snapshot.cpp
--- a/src/snapshot.cpp
+++ b/src/snapshot.cpp
@@ -110,12 +110,12 @@ void Snapshot::setName(QString name)
 
 unsigned Snapshot::numChannels() const
 {
-    return data.size();
+    return yData.size();
 }
 
 unsigned Snapshot::numSamples() const
 {
-    return data[0].size();
+    return yData[0]->size();
 }
 
 const ChannelInfoModel* Snapshot::infoModel() const
@@ -135,31 +135,27 @@ QString Snapshot::channelName(unsigned c
 
 void Snapshot::save(QString fileName)
 {
-    // TODO: remove code duplication (MainWindow::onExportCsv)
     QSaveFile file(fileName);
 
     if (file.open(QIODevice::WriteOnly | QIODevice::Text))
     {
         QTextStream fileStream(&file);
 
-        unsigned numOfChannels = data.size();
-        unsigned numOfSamples = data[0].size();
-
         // print header
-        for (unsigned int ci = 0; ci < numOfChannels; ci++)
+        for (unsigned int ci = 0; ci < numChannels(); ci++)
         {
             fileStream << channelName(ci);
-            if (ci != numOfChannels-1) fileStream << ",";
+            if (ci != numChannels()-1) fileStream << ",";
         }
         fileStream << '\n';
 
         // print rows
-        for (unsigned int i = 0; i < numOfSamples; i++)
+        for (unsigned int i = 0; i < numSamples(); i++)
         {
-            for (unsigned int ci = 0; ci < numOfChannels; ci++)
+            for (unsigned int ci = 0; ci < numChannels(); ci++)
             {
-                fileStream << data[ci][i].y();
-                if (ci != numOfChannels-1) fileStream << ",";
+                fileStream << yData[ci]->sample(i);
+                if (ci != numChannels()-1) fileStream << ",";
             }
             fileStream << '\n';
         }