Simplify lq.math implementations

larq/__init__.py

@@ -12,6 +12,8 @@
     utils,
 )
 
+utils._check_lce_version()
+
 try:
     from importlib import metadata  # type: ignore
 except ImportError:

larq/math.py

@@ -22,7 +22,8 @@ def sign(x):
     # Returns
         A Tensor with same type as `x`.
     """
-    return tf.sign(tf.sign(x) + 0.1)
+    ones = tf.ones_like(x)
+    return tf.where(x >= 0, ones, -ones)
 
 
 def heaviside(x):
@@ -41,4 +42,4 @@ def heaviside(x):
     # Returns
         A Tensor with same type as `x`.
     """
-    return tf.sign(tf.nn.relu(x))
+    return tf.where(x > 0, tf.ones_like(x), tf.zeros_like(x))

larq/utils.py

@@ -1,7 +1,15 @@
+import warnings
 from contextlib import contextmanager
 
+from packaging import version
 from tensorflow.keras.utils import get_custom_objects
 
+try:
+    from importlib import metadata  # type: ignore
+except ImportError:
+    # Running on pre-3.8 Python; use importlib-metadata package
+    import importlib_metadata as metadata  # type: ignore
+
 
 def memory_as_readable_str(num_bits: int) -> str:
     """Generate a human-readable string for the memory size.
@@ -68,3 +76,15 @@ def patch_object(object, name, value):
     setattr(object, name, value)
     yield
     setattr(object, name, old_value)
+
+
+def _check_lce_version():
+    try:
+        lce_version = metadata.version("larq-compute-engine")
+        if version.parse(lce_version) < version.parse("0.6.1"):
+            warnings.warn(
+                f"larq-compute-engine={lce_version} is not supported by this version of larq.\n"
+                "Please upgrade larq-compute-engine to v0.6.1 or newer."
+            )
+    except metadata.PackageNotFoundError:
+        pass

setup.py

@@ -20,6 +20,7 @@ def readme():
     license="Apache 2.0",
     install_requires=[
         "numpy >= 1.15.4, < 2.0",
+        "packaging>=19.2,<22.0",
         "terminaltables>=3.1.0",
         "dataclasses ; python_version<'3.7'",
         "importlib-metadata >= 2.0, < 4.0 ; python_version<'3.8'",
@@ -31,7 +32,6 @@ def readme():
             "black==21.6b0",
             "flake8>=3.7.9,<3.10.0",
             "isort==5.9.2",
-            "packaging>=19.2,<22.0",
             "pytest>=5.2.4,<6.3.0",
             "pytest-cov>=2.8.1,<2.13.0",
             "pytest-xdist>=1.30,<2.4",