问TensorBoard -在同一图上绘制训练和验证损失？

EN

# + <
# We need these to make a custom protocol buffer to display custom scalars.
# See https://developers.google.com/protocol-buffers/
from tensorboard.plugins.custom_scalar import layout_pb2
from tensorboard.summary.v1 import custom_scalar_pb
#   > 
import tensorflow as tf
from time import time
import re

# Initial values
(x0, y0) = (-1, 1)

# This is useful only when re-running code (e.g. Jupyter).
tf.reset_default_graph()  

# Set up variables.
x = tf.Variable(x0, name="X", dtype=tf.float64)
y = tf.Variable(y0, name="Y", dtype=tf.float64)

# Define loss function and give it a name.
loss = tf.square(x - 3*y) + tf.square(x+y)
loss = tf.identity(loss, name='my_loss')

# Define the op for performing gradient descent.
minimize_step_op = tf.train.GradientDescentOptimizer(0.092).minimize(loss)

# List quantities to summarize in a dictionary 
# with (key, value) = (name, Tensor).
to_summarize = dict(
    X = x,
    Y_plus_2 = y + 2,
)

# Build scalar summaries corresponding to to_summarize.
# This should be done in a separate name scope to avoid name collisions
# between summaries and their respective tensors. The name scope also
# gives a title to a group of scalars in TensorBoard.
with tf.name_scope('scalar_summaries'):
    my_var_summary_op = tf.summary.merge(
        [tf.summary.scalar(name, var) 
            for name, var in to_summarize.items()
        ]
    )

# + <
# This constructs the layout for the custom scalar, and specifies
# which scalars to plot.
layout_summary = custom_scalar_pb(
    layout_pb2.Layout(category=[
        layout_pb2.Category(
            title='Custom scalar summary group',
            chart=[
                layout_pb2.Chart(
                    title='Custom scalar summary chart',
                    multiline=layout_pb2.MultilineChartContent(
                        # regex to select only summaries which 
                        # are in "scalar_summaries" name scope:
                        tag=[r'^scalar_summaries\/']
                    )
                )
            ])
    ])
)
#   >

# Create session.
with tf.Session() as sess:

    # Initialize session.
    sess.run(tf.global_variables_initializer())

    # Create writer.
    with tf.summary.FileWriter(f'./logs/session_{int(time())}') as writer:

        # Write the session graph.
        writer.add_graph(sess.graph) # (not necessary for scalars)

# + <
        # Define the layout for creating custom scalars in terms
        # of the scalars.
        writer.add_summary(layout_summary)
#   >

        # Main iteration loop.
        for i in range(50):
            current_summary = sess.run(my_var_summary_op)
            writer.add_summary(current_summary, global_step=i)
            writer.flush()
            sess.run(minimize_step_op)   

# + <
        [code to add custom scalars goes here]
#   >