+TODO: test computeMedoids + filter
+# #R-equivalent, requiring a matrix (thus potentially breaking "fit-in-memory" hope)
+# mat_meds = medoids[,]
+# mi = rep(NA,nb_series)
+# for (i in 1:nb_series)
+# mi[i] <- which.min( rowSums( sweep(mat_meds, 2, ref_series[i,], '-')^2 ) )
+# rm(mat_meds); gc()
+