Tensorflow. How to tensorboard

So I have this code that works until I want it to draw tensorboard for me:

import numpy as np
import tensorflow as tf
import tqdm
from sklearn.model_selection import train_test_split
from tensorflow.python.framework import ops

ops.reset_default_graph()

x = np.linspace(0, 10, 1000, dtype='float32')
y = np.sin(x) + np.random.normal(size=len(x))

X_train, X_test, y_train, y_test = train_test_split(x, y, test_size=.3)

x_ = tf.placeholder(name="input", shape=None, dtype=np.float32)
y_ = tf.placeholder(name="output", shape=None, dtype=np.float32)
w = tf.Variable(tf.random_normal([]), name='w')
b = tf.Variable(tf.random_normal([]), name='bias')

model_output = tf.add(tf.multiply(x_, w), b)

loss = tf.reduce_mean(tf.pow(y_ - model_output, 2), name='loss')
train_step = tf.train.GradientDescentOptimizer(0.0025).minimize(loss)

summary_writer = tf.summary.FileWriter('linreg')
for value in [x_, model_output, w, loss]:
    tf.summary.scalar(value.op.name, value)
summaries = tf.summary.merge_all()

n_epochs = 100
train_errors = []
test_errors = []

with tf.Session() as sess:
    sess.run(tf.global_variables_initializer())
    for i in tqdm.tqdm(range(n_epochs)):  # 100
        _, train_err = sess.run([train_step, loss],
                                feed_dict={x_: X_train, y_: y_train})
        train_errors.append(train_err)
        test_errors.append(
            sess.run(loss, feed_dict={x_: X_test, y_: y_test}))

        summary_writer.add_summary(sess.run(summaries), i)

with this I'm getting:

InvalidArgumentError (see above for traceback): You must feed a value for placeholder tensor 'input' with dtype float
     [[Node: input = Placeholder[dtype=DT_FLOAT, shape=[], _device="/job:localhost/replica:0/task:0/cpu:0"]()]]

so if I understood correctly it asked me to feed_dict, okay lets modify last line:

summary_writer.add_summary(sess.run(summaries, feed_dict={x_: X_train, y_: y_train}), i)

and now we have:

InvalidArgumentError (see above for traceback): tags and values not the same shape: [] != [700] (tag 'input_1')
     [[Node: input_1 = ScalarSummary[T=DT_FLOAT, _device="/job:localhost/replica:0/task:0/cpu:0"](input_1/tags, _recv_input_0)]]

so, weight wants to be same shape as x, I can do that:

w = tf.Variable(tf.random_normal([700]), name='w')

but what about X_test? it has only 300 rows:

InvalidArgumentError (see above for traceback): Incompatible shapes: [300] vs. [700]
     [[Node: Mul = Mul[T=DT_FLOAT, _device="/job:localhost/replica:0/task:0/cpu:0"](_recv_input_0, w/read)]]

so should I dynamically change w shape? or get w1 and w2 for train and test? how to tensorboard?

========================================================================

Shape time. After shape specification on variables and placeholders:

x_ = tf.placeholder(name="input", shape=[None, 1], dtype=np.float32)
y_ = tf.placeholder(name="output", shape=[None, 1], dtype=np.float32)
w = tf.Variable(tf.random_normal([1, 1]), name='w')
b = tf.Variable(tf.random_normal([1]), name='bias')

We can see that out data should be in shape too:

ValueError: Cannot feed value of shape (700,) for Tensor 'input:0', which has shape '(?, 1)'

so last piece of code looks like this (added reshapes on data):

with tf.Session() as sess:
    sess.run(tf.global_variables_initializer())
    for i in tqdm.tqdm(range(n_epochs)):

        _, train_err, summ = sess.run([train_step, loss, summaries],
                                feed_dict={x_: X_train.reshape(len(X_train), 1), y_: y_train.reshape(len(y_train), 1)})
        summary_writer.add_summary(summ, i)

        train_errors.append(train_err)
        test_errors.append(
            sess.run(loss, feed_dict={x_: X_test.reshape(len(X_test), 1), y_: y_test.reshape(len(y_test), 1)}))

And current error:

InvalidArgumentError (see above for traceback): tags and values not the same shape: [] != [1,1] (tag 'w_1')
         [[Node: w_1 = ScalarSummary[T=DT_FLOAT, _device="/job:localhost/replica:0/task:0/cpu:0"](w_1/tags, w/read)]]

Now, I don't even get what tensor has a shape of [].

==============================================================

Conclusion time.

tf.summary.scalar([value.op.name], value)

won't do, coz first/name argument of tf.summary.scalar wants string or byte, and gives error otherwise.

So name would be shape of [] anyway, lets accept it and change code a bit:

w = tf.Variable(tf.random_normal([]), name='w')
b = tf.Variable(tf.random_normal([]), name='bias')
...
for value in [w, b, loss]:
    tf.summary.scalar(value.op.name, value)

finally works

Solution

x_ is a placeholder, that will contain your input values. It does not have any fixed value in the graph, its only value is the ones you feed. So you just need to use:

    summary_writer.add_summary(sess.run(summaries, feed_dict={x_: X_train, y_: y_train}), i)

But doing it like that would make you compute everything twice. What you should rather use is:

_, train_err, summ = sess.run([train_step, loss, summaries],
                            feed_dict={x_: X_train, y_: y_train})
summary_writer.add_summary(summ, i)

That way your training step and summary computation happen all at once.

EDIT:

It looks like you just have shaping issues, that are only revealed by tensorboard...

your placeholder x_ should be declared of shape [None, n_features] (here, n_features = 1, so you can also have it working with just [None]. I don't really know what None does, maybe your problems come from that maybe not...)
y should be of shape [None, n_outputs], so [None, 1] here. Probably None or [None] also work.
w should be of shape [n_features, n_outputs], in your case [1, 1]. You can't have it shaped after the batch size, this is a nonsense in terms of machine learning (at least if you're trying to learn sin(x) from x alone and not from the rest of the batch, which would not make much sense)
b should be of shape [n_outputs], so [1] here.

Does it work if you specify all these shapes ?

EDIT 2

It is a shaping problem. The answer is given here, it seems you just have to replace

tf.summary.scalar(value.op.name, value)

with

tf.summary.scalar([value.op.name], value)