hparams: fix demo (remove group_name argument) (#2258)

Summary:
In #2188, I removed the `group_name` parameter from the Keras callback,
but forgot to remove it from the call site in the demo code.

Test Plan:
Running `bazel run //tensorboard/plugins/hparams:hparams_demo` now
works. Previously, it failed with the error, “unexpected keyword
argument 'group_name'”.

wchargin-branch: hparams-demo-no-group-name

Author: wchargin

tensorboard/plugins/hparams/hparams_demo.py

@@ -23,7 +23,6 @@
 from __future__ import division
 from __future__ import print_function
 
-import hashlib
 import math
 import os.path
 import random
@@ -161,7 +160,7 @@ def model_fn(hparams, seed):
   return model
 
 
-def run(data, base_logdir, session_id, group_id, hparams):
+def run(data, base_logdir, session_id, hparams):
   """Run a training/validation session.
 
   Flags must have been parsed for this function to behave.
@@ -170,8 +169,6 @@ def run(data, base_logdir, session_id, group_id, hparams):
     data: The data as loaded by `prepare_data()`.
     base_logdir: The top-level logdir to which to write summary data.
     session_id: A unique string ID for this session.
-    group_id: The string ID of the session group that includes this
-      session.
     hparams: A dict mapping hyperparameters in `HPARAMS` to values.
   """
   model = model_fn(hparams=hparams, seed=session_id)
@@ -182,7 +179,7 @@ def run(data, base_logdir, session_id, group_id, hparams):
       update_freq=flags.FLAGS.summary_freq,
       profile_batch=0,  # workaround for issue #2084
   )
-  hparams_callback = hp.KerasCallback(logdir, hparams, group_name=group_id)
+  hparams_callback = hp.KerasCallback(logdir, hparams)
   ((x_train, y_train), (x_test, y_test)) = data
   result = model.fit(
       x=x_train,
@@ -224,7 +221,6 @@ def run_all(logdir, verbose=False):
   for group_index in xrange(flags.FLAGS.num_session_groups):
     hparams = {h: sample_uniform(h.domain, rng) for h in HPARAMS}
     hparams_string = str(hparams)
-    group_id = hashlib.sha256(hparams_string.encode("utf-8")).hexdigest()
     for repeat_index in xrange(sessions_per_group):
       session_id = str(session_index)
       session_index += 1
@@ -239,7 +235,6 @@ def run_all(logdir, verbose=False):
           data=data,
           base_logdir=logdir,
           session_id=session_id,
-          group_id=group_id,
           hparams=hparams,
       )