From 6a76f98f65b32f84ef9051a6d49b7fd3d8fd8451 Mon Sep 17 00:00:00 2001
From: Andrew <andrewgfullard@gmail.com>
Date: Wed, 4 May 2022 16:15:43 -0400
Subject: [PATCH] Revert "Removing Levels Index Variable Within Atomic Data
 Preperation (#1957)"

This reverts commit 507c50f382ba1e07441e549edcebce3c7216211e.
---
 tardis/io/atom_data/base.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/tardis/io/atom_data/base.py b/tardis/io/atom_data/base.py
index e8758a5b0d8..28cd820da31 100644
--- a/tardis/io/atom_data/base.py
+++ b/tardis/io/atom_data/base.py
@@ -330,6 +330,10 @@ def prepare_atom_data(
 
         self.nlte_species = nlte_species
 
+        self.levels_index = pd.Series(
+            np.arange(len(self.levels), dtype=int), index=self.levels.index
+        )
+
         # cutting levels_lines
         self.lines = self.lines[
             self.lines.index.isin(
@@ -348,10 +352,22 @@ def prepare_atom_data(
             "level_number_upper"
         )
 
+        self.lines_lower2level_idx = (
+            self.levels_index.loc[tmp_lines_lower2level_idx]
+            .astype(np.int64)
+            .values
+        )
+
         tmp_lines_upper2level_idx = self.lines.index.droplevel(
             "level_number_lower"
         )
 
+        self.lines_upper2level_idx = (
+            self.levels_index.loc[tmp_lines_upper2level_idx]
+            .astype(np.int64)
+            .values
+        )
+
         if (
             self.macro_atom_data_all is not None
             and not line_interaction_type == "scatter"