prepost.simchunks: add optional non-zero offset when numbering chunks

wetb/prepost/simchunks.py

@@ -35,7 +35,7 @@ from wetb.prepost.Simulations import Cases
 def create_chunks_htc_pbs(cases, sort_by_values=['[Windspeed]'], ppn=20,
                           nr_procs_series=9, processes=1, queue='workq',
                           walltime='24:00:00', chunks_dir='zip-chunks-jess',
-                          pyenv='wetb_py3'):
+                          pyenv='wetb_py3', i0=0):
     """Group a large number of simulations htc and pbs launch scripts into
     different zip files so we can run them with find+xargs on various nodes.
     """
@@ -405,8 +405,8 @@ def create_chunks_htc_pbs(cases, sort_by_values=['[Windspeed]'], ppn=20,
     df_ind = pd.DataFrame(columns=['chnk_nr'], dtype=np.int32)
     df_ind.index.name = '[case_id]'
     for ii, dfi in enumerate(df_iter):
-        fname, ind = make_zip_chunks(dfi, ii, sim_id, run_dir, model_zip)
-        make_pbs_chunks(dfi, ii, sim_id, run_dir, model_zip)
+        fname, ind = make_zip_chunks(dfi, i0+ii, sim_id, run_dir, model_zip)
+        make_pbs_chunks(dfi, i0+ii, sim_id, run_dir, model_zip)
         df_ind = df_ind.append(ind)
         print(fname)