accuracy_summary = tf.scalar_summary('Training Accuracy', accuracy)
tf.scalar_summary('SomethingElse', foo)
summary_op = tf.merge_all_summaries()
summaries_dir = '/me/mydir/'
train_writer = tf.train.SummaryWriter(summaries_dir + '/train', sess.graph)
test_writer = tf.train.SummaryWriter(summaries_dir + '/test')
Show training and validation accuracy in TensorFlow using same graph