fix the order of the X and Y axes in REL_DIAG

include/evalhyd/detail/probabilist/ranks.hpp

@@ -184,7 +184,8 @@ namespace evalhyd
 
         namespace metrics
         {
-            /// Compute the reliability diagram X and Y axes.
+            /// Compute the reliability diagram X and Y axes, the forecast
+            /// probability and the observed relative frequency, respectively.
             ///
             /// \param o_j
             ///     Tallies of streamflow observations for all possible ranks.
@@ -238,19 +239,21 @@ namespace evalhyd
                         // calculate length of subset
                         auto l = xt::sum(t_msk_sampled, -1);
 
+                        // compute the forecast probability $y_i$
+                        // [X-axis]
+                        xt::view(REL_DIAG, xt::all(), xt::all(), m, e, xt::all(), 0) =
+                                xt::arange<double>(double(n_mbr + 1)) / n_mbr;
+
                         // compute the observed relative frequency
+                        // [Y-axis]
                         // $\bar{o_j} = \frac{1}{n} \sum_{k \in M_j} r_k$
-                        xt::view(REL_DIAG, xt::all(), xt::all(), m, e, xt::all(), 0) =
+                        xt::view(REL_DIAG, xt::all(), xt::all(), m, e, xt::all(), 1) =
                                 xt::cumsum(
                                         xt::view(o_j, xt::all(), xt::all(),
                                                  m, e, xt::all())
                                         / l,
                                         -1
                                 );
-
-                        // compute the forecast probability $y_i$
-                        xt::view(REL_DIAG, xt::all(), xt::all(), m, e, xt::all(), 1) =
-                                xt::arange<double>(double(n_mbr + 1)) / n_mbr;
                     }
                 }