Add HAS_NUMPY in order to avoid 'numpy' in sys.modules every time

python/pyarrow/__init__.py

@@ -73,6 +73,10 @@ def parse_git(root, **kwargs):
                          io_thread_count, set_io_thread_count)
 
 
+# Expose whether NUMPY is available or not
+from pyarrow.lib import HAS_NUMPY
+
+
 def show_versions():
     """
     Print various version information, to help with error reporting.

python/pyarrow/_compute.pyx

@@ -24,7 +24,7 @@ from cython.operator cimport dereference as deref
 
 from collections import namedtuple
 
-from pyarrow.lib import frombytes, tobytes, ArrowInvalid
+from pyarrow.lib import frombytes, tobytes, ArrowInvalid, HAS_NUMPY
 from pyarrow.lib cimport *
 from pyarrow.includes.common cimport *
 from pyarrow.includes.libarrow cimport *
@@ -476,7 +476,7 @@ cdef class MetaFunction(Function):
 
 cdef _pack_compute_args(object values, vector[CDatum]* out):
     for val in values:
-        if "numpy" in sys.modules and isinstance(val, (list, np.ndarray)):
+        if HAS_NUMPY and isinstance(val, (list, np.ndarray)):
             val = lib.asarray(val)
 
         if isinstance(val, Array):

python/pyarrow/lib.pyx

@@ -21,8 +21,10 @@
 
 import datetime
 import decimal as _pydecimal
+HAS_NUMPY=False
 try:
     import numpy as np
+    HAS_NUMPY=True
 except ImportError:
     np = None
 import os

python/pyarrow/tests/test_array.py

@@ -486,7 +486,7 @@ def test_array_slice():
             res.validate()
             expected = arr.to_pylist()[start:stop]
             assert res.to_pylist() == expected
-            if "numpy" in sys.modules:
+            if pa.HAS_NUMPY:
                 assert res.to_numpy().tolist() == expected