breaking: deprecate sagemaker.utils.to_str() (#1621)

This method was written for Python 2 compatibility.
For Python 3+, it is the same as simply calling str().

Author: laurenyu

src/sagemaker/parameter.py

@@ -14,8 +14,6 @@
 from __future__ import absolute_import
 import json
 
-from sagemaker.utils import to_str
-
 
 class ParameterRange(object):
     """Base class for representing parameter ranges. This is used to define what
@@ -71,8 +69,8 @@ def as_tuning_range(self, name):
         """
         return {
             "Name": name,
-            "MinValue": to_str(self.min_value),
-            "MaxValue": to_str(self.max_value),
+            "MinValue": str(self.min_value),
+            "MaxValue": str(self.max_value),
             "ScalingType": self.scaling_type,
         }
 
@@ -111,9 +109,9 @@ def __init__(self, values):  # pylint: disable=super-init-not-called
                 This input will be converted into a list of strings.
         """
         if isinstance(values, list):
-            self.values = [to_str(v) for v in values]
+            self.values = [str(v) for v in values]
         else:
-            self.values = [to_str(values)]
+            self.values = [str(values)]
 
     def as_tuning_range(self, name):
         """Represent the parameter range as a dicionary suitable for a request
@@ -158,7 +156,7 @@ def cast_to_type(cls, value):
         Args:
             value:
         """
-        return to_str(value)
+        return str(value)
 
 
 class IntegerParameter(ParameterRange):

src/sagemaker/tuner.py

@@ -37,7 +37,7 @@
 )
 from sagemaker.session import Session
 from sagemaker.session import s3_input
-from sagemaker.utils import base_name_from_image, name_from_base, to_str
+from sagemaker.utils import base_name_from_image, name_from_base
 
 AMAZON_ESTIMATOR_MODULE = "sagemaker"
 AMAZON_ESTIMATOR_CLS_NAMES = {
@@ -345,9 +345,7 @@ def _prepare_static_hyperparameters(
     ):
         """Prepare static hyperparameters for one estimator before tuning"""
         # Remove any hyperparameter that will be tuned
-        static_hyperparameters = {
-            to_str(k): to_str(v) for (k, v) in estimator.hyperparameters().items()
-        }
+        static_hyperparameters = {str(k): str(v) for (k, v) in estimator.hyperparameters().items()}
         for hyperparameter_name in hyperparameter_ranges.keys():
             static_hyperparameters.pop(hyperparameter_name, None)
 

src/sagemaker/utils.py

@@ -20,7 +20,6 @@
 import random
 import re
 import shutil
-import sys
 import tarfile
 import tempfile
 import time
@@ -162,25 +161,6 @@ def get_short_version(framework_version):
     return ".".join(framework_version.split(".")[:2])
 
 
-def to_str(value):
-    """Convert the input to a string, unless it is a unicode string in Python 2.
-
-    Unicode strings are supported as native strings in Python 3, but
-    ``str()`` cannot be invoked on unicode strings in Python 2, so we need to
-    check for that case when converting user-specified values to strings.
-
-    Args:
-        value: The value to convert to a string.
-
-    Returns:
-        str or unicode: The string representation of the value or the unicode
-        string itself.
-    """
-    if sys.version_info.major < 3 and isinstance(value, six.string_types):
-        return value
-    return str(value)
-
-
 def extract_name_from_job_arn(arn):
     """Returns the name used in the API given a full ARN for a training job or
     hyperparameter tuning job.

tests/unit/test_utils.py

@@ -92,16 +92,6 @@ def test_unique_name_from_base_truncated():
     )
 
 
-def test_to_str_with_native_string():
-    value = "some string"
-    assert sagemaker.utils.to_str(value) == value
-
-
-def test_to_str_with_unicode_string():
-    value = u"åñøthér strîng"
-    assert sagemaker.utils.to_str(value) == value
-
-
 def test_name_from_tuning_arn():
     arn = "arn:aws:sagemaker:us-west-2:968277160000:hyper-parameter-tuning-job/resnet-sgd-tuningjob-11-07-34-11"
     name = sagemaker.utils.extract_name_from_job_arn(arn)