Merge pull request #2843 from nicolossus/nestsonata_pandas

NEST-SONATA: Enclose `pandas` import in `try` block

pynest/nest/lib/hl_api_sonata.py

@@ -25,7 +25,6 @@
 from pathlib import Path, PurePath
 
 import numpy as np
-import pandas as pd
 
 from .. import pynestkernel as kernel
 from ..ll_api import sli_func, sps, sr
@@ -34,6 +33,13 @@
 from .hl_api_simulation import SetKernelStatus, Simulate
 from .hl_api_types import NodeCollection
 
+try:
+    import pandas as pd
+
+    have_pandas = True
+except ImportError:
+    have_pandas = False
+
 try:
     import h5py
 
@@ -101,6 +107,9 @@ def __init__(self, config, sim_config=None):
         if not have_h5py:
             msg = "SonataNetwork unavailable because h5py is not installed or could not be imported"
             raise kernel.NESTError(msg)
+        if not have_pandas:
+            msg = "SonataNetwork unavailable because pandas is not installed or could not be imported"
+            raise kernel.NESTError(msg)
 
         self._node_collections = {}
         self._edges_maps = []