ENH: Use elementwise comparisons with 0 rather than boolean casting

1 files changed, 6 insertions, 2 deletions

diff --git a/numpy/lib/function_base.py b/numpy/lib/function_base.py
index cd8862c94..96e1c6de9 100644
--- a/numpy/lib/function_base.py
+++ b/numpy/lib/function_base.py
@@ -1631,7 +1631,7 @@ def trim_zeros(filt, trim='fb'):
         # Numpy 1.20.0, 2020-07-31
         warning = DeprecationWarning(
             "in the future trim_zeros will require a 1-D array as input "
-            "that is compatible with ndarray.astype(bool)"
+            "that supports elementwise comparisons with zero"
         )
         warning.__cause__ = ex
         warnings.warn(warning, stacklevel=3)
@@ -1643,7 +1643,11 @@ def trim_zeros(filt, trim='fb'):
 
 def _trim_zeros_new(filt, trim='fb'):
     """Newer optimized implementation of ``trim_zeros()``."""
-    arr = np.asanyarray(filt).astype(bool, copy=False)
+    arr_any = np.asanyarray(filt)
+    with warnings.catch_warnings():
+        # not all dtypes support elementwise comparisons with `0` (e.g. str)
+        warnings.simplefilter('error', FutureWarning)
+        arr = arr_any != 0 if arr_any.dtype != bool else arr_any
 
     if arr.ndim != 1:
         raise ValueError('trim_zeros requires an array of exactly one dimension')