update zebra library to be able to use links

This commit updates the zebra library files zebra.{c,h} so that it's now
possible to traverse the data structure using links! This was originally
motivated by wanting to figure out which MC particles were generated from the
MCGN bank (from which it's only possible to access the tracks and vertices
using structural links).

I've also added a new test to test-zebra which checks the consistency of all of
the next/up/orig, structural, and reference links in a zebra file.

2 files changed, 16 insertions, 16 deletions

diff --git a/utils/plot b/utils/plot
index 59eb4c2..d671016 100755
--- a/utils/plot
+++ b/utils/plot
@@ -75,7 +75,7 @@ if __name__ == '__main__':
         psi = []
         for event in data['data']:
             # get the particle ID
-            id = event['mctk'][-1]['id']
+            id = event['mcgn'][0]['id']
 
             if 'ev' not in event:
                 continue
@@ -88,24 +88,24 @@ if __name__ == '__main__':
             mass = SNOMAN_MASS[id]
             # for some reason it's the *second* track which seems to contain the
             # initial energy
-            true_energy = event['mctk'][-1]['energy']
+            true_energy = event['mcgn'][0]['energy']
             # The MCTK bank has the particle's total energy (except for neutrons)
             # so we need to convert it into kinetic energy
             ke = true_energy - mass
             energy = fit[id]['energy']
             dT.append(energy-ke)
-            true_posx = event['mcvx'][0]['posx']
+            true_posx = event['mcgn'][0]['posx']
             posx = fit[id]['posx']
             dx.append(posx-true_posx)
-            true_posy = event['mcvx'][0]['posy']
+            true_posy = event['mcgn'][0]['posy']
             posy = fit[id]['posy']
             dy.append(posy-true_posy)
-            true_posz = event['mcvx'][0]['posz']
+            true_posz = event['mcgn'][0]['posz']
             posz = fit[id]['posz']
             dz.append(posz-true_posz)
-            dirx = event['mctk'][-1]['dirx']
-            diry = event['mctk'][-1]['diry']
-            dirz = event['mctk'][-1]['dirz']
+            dirx = event['mcgn'][0]['dirx']
+            diry = event['mcgn'][0]['diry']
+            dirz = event['mcgn'][0]['dirz']
             true_dir = [dirx,diry,dirz]
             true_dir = np.array(true_dir)/np.linalg.norm(true_dir)
             theta = fit[id]['theta']
diff --git a/utils/plot-fit-results b/utils/plot-fit-results
index 48d922a..c3d3f16 100755
--- a/utils/plot-fit-results
+++ b/utils/plot-fit-results
@@ -84,7 +84,7 @@ if __name__ == '__main__':
 
         for i, event in enumerate(data['data']):
             # get the particle ID
-            id = event['mctk'][-1]['id']
+            id = event['mcgn'][0]['id']
 
             a[i]['id'] = id
 
@@ -95,7 +95,7 @@ if __name__ == '__main__':
             mass = SNOMAN_MASS[id]
             # for some reason it's the *second* track which seems to contain the
             # initial energy
-            true_energy = event['mctk'][-1]['energy']
+            true_energy = event['mcgn'][0]['energy']
             # The MCTK bank has the particle's total energy (except for neutrons)
             # so we need to convert it into kinetic energy
             ke = true_energy - mass
@@ -107,21 +107,21 @@ if __name__ == '__main__':
             a[i]['dT'] = energy-ke
 
             # store the fit position residuals
-            true_posx = event['mcvx'][0]['posx']
+            true_posx = event['mcgn'][0]['posx']
             posx = fit[id]['posx']
             a[i]['dx'] = posx-true_posx
-            true_posy = event['mcvx'][0]['posy']
+            true_posy = event['mcgn'][0]['posy']
             posy = fit[id]['posy']
             a[i]['dy'] = posy-true_posy
-            true_posz = event['mcvx'][0]['posz']
+            true_posz = event['mcgn'][0]['posz']
             posz = fit[id]['posz']
             a[i]['dz'] = posz-true_posz
 
             # compute the angle between the fit direction and the true
             # direction
-            dirx = event['mctk'][-1]['dirx']
-            diry = event['mctk'][-1]['diry']
-            dirz = event['mctk'][-1]['dirz']
+            dirx = event['mcgn'][0]['dirx']
+            diry = event['mcgn'][0]['diry']
+            dirz = event['mcgn'][0]['dirz']
             true_dir = [dirx,diry,dirz]
             true_dir = np.array(true_dir)/np.linalg.norm(true_dir)
             theta = fit[id]['theta']