don’t include empty evalables to begin with

python/loadleveller/mcextract.py

@@ -42,10 +42,10 @@ class MCArchive:
                     o.error = np.zeros([self.num_tasks, len(value['error'])]) + np.nan
 
                     if o.mean.shape != o.error.shape:
-                        raise 'observable "{}": dimension mismatch between mean and error'.format(obs)
+                        raise Exception('observable "{}": dimension mismatch between mean and error'.format(obs))
                 else:
                     if len(value['mean']) != o.mean.shape[1] or len(value['error']) != o.error.shape[1]:
-                        raise 'observable "{}": dimension mismatch between different tasks'.format(obs)
+                        raise Exception('observable "{}": dimension mismatch between different tasks'.format(obs))
 
                 o.mean[i,:] = value['mean']
                 o.error[i,:] = value['error']

src/evalable.cpp

 #include "evalable.h"
 #include "measurements.h"
 #include <fmt/format.h>
-#include <map>
 #include <iostream>
+#include <map>
 
 namespace loadl {
 
@@ -28,7 +28,10 @@ void evalable::jackknife(const results &res, observable_result &obs_res) const {
 	size_t bin_count = -1; // maximal value
 	for(const auto &obs_name : used_observables_) {
 		if(res.observables.count(obs_name) <= 0) {
-			std::cerr << fmt::format("Warning: evalable '{}': used observable '{}' not found in Monte Carlo results. Skipping...", name_, obs_name);
+			std::cerr << fmt::format(
+			    "Warning: evalable '{}': used observable '{}' not found in Monte Carlo results. "
+			    "Skipping...",
+			    name_, obs_name);
 			return;
 		}
 		const auto &obs = res.observables.at(obs_name);

src/merger.cpp

@@ -13,9 +13,13 @@ namespace loadl {
 static void evaluate_evalables(results &res, const std::vector<evalable> &evalables) {
 	std::vector<observable_result> evalable_results;
 	for(auto &eval : evalables) {
-		evalable_results.emplace_back();
+		observable_result o;
+		eval.jackknife(res, o);
 
-		eval.jackknife(res, evalable_results.back());
+		// don’t include empty results
+		if(o.rebinning_bin_count > 0) {
+			evalable_results.emplace_back(o);
+		}
 	}
 
 	for(auto &eval : evalable_results) {