remove the T in dataset printing and json dumping

include/data/FluidDataSeries.hpp

@@ -299,21 +299,21 @@ class FluidDataSeries
     if (series.rows() < maxFrames)
     {
       for (index t = 0; t < series.rows(); t++)
-        result << setw(10) << "t" << t << ": "
+        result << setw(10) << t << ": "
                << printFrame(series.row(t), maxCols) << endl;
     }
     else
     {
       for (index t = 0; t < maxFrames / 2; t++)
-        result << setw(10) << "t" << t << ": "
+        result << setw(10) << t << ": "
                << printFrame(series.row(t), maxCols) << endl;
 
       result << setw(10) << "..." << std::endl;
 
       for (index t = maxFrames / 2; t > 0; t--)
       {
         index rownum = series.rows() - t;
-        result << setw(10) << "t" << (rownum) << ": "
+        result << setw(10) << (rownum) << ": "
                << printFrame(series.row(rownum), maxCols) << endl;
       }
     }

include/data/FluidJSON.hpp

@@ -142,12 +142,20 @@ void to_json(nlohmann::json &j, const FluidDataSeries<std::string, T, 1> &ds) {
   auto ids = ds.getIds();
   auto data = ds.getData();
   j["cols"] = ds.pointSize();
-  char timestring[6];
+  index maxlength = 0;
+  for (index r = 0; r < ds.size(); r++) {
+    auto length = data[r].rows();
+      maxlength = std::max(maxlength, length);
+  }
+  index stringlen = std::ceil(std::log10(maxlength-1));
+  std::stringstream timestring;
   for (index r = 0; r < ds.size(); r++) {
     auto series = data[r];
     for (index s = 0; s < series.rows(); s++) {
-      std::snprintf(timestring,6,"T%04ld",s);
-      j["data"][ids[r]][timestring] = data[r].row(s);
+        timestring.str("");
+        timestring.clear();
+      timestring << std::setw(stringlen) << std::setfill('0') << s;
+      j["data"][ids[r]][timestring.str()] = data[r].row(s);
     }
   }
 }