Q:

Tensorboard- superimpose 2 plots

In tensorboard, I would like to superimpose 2 plots on the same graph (training and validation losses of a neural network). 
I can see 2 separate plots, but not one plot with 2 superimposed curves.  Otherwise, I get one plot in zigzag. 
How can I do? 

A:

It is possible to superimpose two plots in Tensorboard.  You'll have to satisfy both of the following:

Create two separate tf.train. SummaryWriter objects such that it outputs in two folders. 
Create two summaries (e.g. tf.scalar_summary) with the same name. 

For example to plot training and validation loss:
# Before training
train_summary = tf.scalar_summary('Loss', train_loss)
vali_summary = tf.scalar_summary('Loss', vali_loss)
train_writer = tf.train. SummaryWriter('/tmp/train'), sess.graph)
vali_writer = tf.train. SummaryWriter('/tmp/vali'), sess.graph)

# And then later
train_writer.add_summary(...)
vali_writer.add_summary(...)

