Add tensorflow as pip optional dependency.

.github/workflows/ci_pip.yml

@@ -28,9 +28,7 @@ jobs:
           sudo apt-get install libsndfile1 ffmpeg
           pip install absl-py
           pip install requests
-          pip install tensorflow-cpu
-          pip install tensorflow-hub
-          pip install git+https://github.com/google-research/perch-hoplite.git
+          pip install "perch_hoplite[tf] @ git+https://github.com/google-research/perch-hoplite.git"
       - name: Test db with unittest
         run: python -m unittest discover -s perch_hoplite/db/tests -p "*test.py"
       - name: Test taxonomy with unittest

perch_hoplite/taxonomy/namespace.py

@@ -22,7 +22,6 @@
 from typing import Iterable
 
 import numpy as np
-import tensorflow as tf
 
 UNKNOWN_LABEL = "unknown"
 
@@ -155,9 +154,7 @@ def to_csv(self) -> str:
       writer.writerow([class_])
     return buffer.getvalue()
 
-  def get_class_map_tf_lookup(
-      self, target_class_list: ClassList
-  ) -> tuple[tf.lookup.StaticHashTable, tf.Tensor]:
+  def get_class_map_tf_lookup(self, target_class_list: ClassList):
     """Create a static hash map for class indices.
 
     Create a lookup table for use in TF Datasets, for, eg, converting between
@@ -173,6 +170,8 @@ def get_class_map_tf_lookup(
       A tensorflow StaticHashTable and an indicator vector for the image of
       the classlist mapping.
     """
+    import tensorflow as tf
+
     if self.namespace != target_class_list.namespace:
       raise ValueError("namespaces must match when creating a class map.")
     intersection = set(self.classes) & set(target_class_list.classes)
@@ -195,7 +194,7 @@ def get_namespace_map_tf_lookup(
       mapping: Mapping,
       keep_unknown: bool | None = None,
       target_class_list: ClassList | None = None,
-  ) -> tf.lookup.StaticHashTable:
+  ):
     """Create a tf.lookup.StaticHasTable for namespace mappings.
 
     Args:
@@ -218,6 +217,8 @@ class list are maintained as unknown in the mapped values. If false then
       ValueError: If a target class list was passed and the namespace of this
       does not match the mapping target namespace.
     """
+    import tensorflow as tf
+
     if UNKNOWN_LABEL in self.classes and keep_unknown is None:
       raise ValueError(
           "'unknown' found in source classes. Explicitly set keep_unknown to"