fix a couple of bugs in plot-energy

This commit fixes two small bugs in the plotting scripts. First, after the HDF5
commit I wasn't correctly computing the particle ID string which I had been
using before which was needed in order to plot things correctly. Second, I
realized that the dataframe groupby function first() actually selects the first
non-null column from each group! What I really wanted was the first row from
each group, so all instances of .first() were updated to .nth(0).

See https://stackoverflow.com/questions/20067636/pandas-dataframe-get-first-row-of-each-group.

1 files changed, 1 insertions, 1 deletions

diff --git a/utils/plot b/utils/plot
index 1bac500..fd5ea51 100755
--- a/utils/plot
+++ b/utils/plot
@@ -90,7 +90,7 @@ if __name__ == '__main__':
             fits = pd.read_hdf(filename, "fits")
 
             # get rid of 2nd events like Michel electrons
-            ev = ev.sort_values(['run','gtid']).groupby(['evn'],as_index=False).first()
+            ev = ev.sort_values(['run','gtid']).groupby(['evn'],as_index=False).nth(0)
 
             # Now, we merge all three datasets together to produce a single
             # dataframe. To do so, we join the ev dataframe with the mcgn frame