tensorfx 0.1.3

TensorFX Framework

Introduction to TensorFX
========================

TensorFX is an end to end application framework to simplifies machine
learning with `TensorFlow <http://tensorflow.org>`__ - both training
models and using them for prediction. It is designed from the ground up
to make the mainline scenarios simple with higher level building blocks,
while ensuring custom or complex scenarios remain possible by preserving
the flexibility of TensorFlow APIs.

There are some important principles that shape the design of the
framework:

1. **Simple, consistent set of usage patterns** Local or cloud, single
node or distributed execution, in-memory data or big data sharded
across files, you should have to write code once, in a single way
regardless of how the code executes.

2. **A Toolbox with Useful Abstractions** The right entrypoint for the
task at hand, starting with off-the-shelf algorithms that let you
focus on feature engineering and hyperparam tuning. If you need to
solve something unqiue, you can focus on building TensorFlow graphs,
rather than infrastructure code (distributed cluster setup,
checkpointing, logging, exporting models etc.).

3. **Declarative** Using YAML, JSON, and simplified Python interfaces to
minimize the amount of boilerplate code.

OK, enough context... here is some information to get you started.

Getting Started
---------------

Once you have a Python environment (recommendation: use Miniconda),
installation is straightforward:

::

pip install tensorflow
pip install tensorfx

Note that TensorFX depends on TensorFlow 1.0, and supporting libraries
such as numpy and pandas.

Documentation
-------------

Documentation is at https://tensorlab.github.io/tensorfx/. This includes
API reference topics, as well as conceptual and how-to topics. They are
a work-in-progress, but check them out! There are a few samples that
demonstrate how to get started as well in the repository. Likewise, more
to be added over time.

Contributions and Development
-----------------------------

We welcome contributions in form of ideas, issues, samples as well as
code. Since the project is at a super-early stage, and evolving rapidly,
its best to start a discussion by filing an issue for any contribution.

Building and Testing
~~~~~~~~~~~~~~~~~~~~

If you want to develop within the repository, clone it, and run the
following commands:

::

# Install requirements and setup envionment
source init.sh install

# Build and Test
./build.sh test

Related Links
~~~~~~~~~~~~~

- Development workflow [TODO: Add wiki entry]

Hello World - Iris Classification Model
---------------------------------------

This sample here is a quick 5-minute introduction to using TensorFX.
Here is the code for building a feed-forward neural network
classification model for the `iris
dataset <https://archive.ics.uci.edu/ml/datasets/Iris>`__.

::

import tensorfx as tfx
import tensorfx.models.nn as nn

# Hyperparameters, training parameters, and data
args, job = nn.FeedForwardClassificationArguments.parse(parse_job=True)
dataset = tfx.data.CsvDataSet(args.data_schema,
train=args.data_train,
eval=args.data_eval,
metadata=args.data_metadata,
features=args.data_features)

# Instantiating the model builder
classification = nn.FeedForwardClassification(args, dataset)

# Training
trainer = tfx.training.ModelTrainer()
model = trainer.train(classification, job)

# Prediction
instances = [
'6.3,3.3,6,2.5', # virginica
'4.4,3,1.3,0.2', # setosa
'6.1,2.8,4.7,1.2' # versicolor
]
predictions = model.predict(instances)

Here's an outline steps to perform for basic usage of what TensorFX
offers:

1. Parse (or build) an Arguments object, usually from the command-line
to define hyperparameters. This object corresponds to the kind of
model you are training, so, ``FeedForwardClassificationArguments`` in
this case.
2. Create a DataSet to reference training and evaluation data, along
with supporting configuration - namely - schema, metadata, and
features (more on these below).
3. Initialize the model builder - in this case
``FeedForwardClassification``.
4. Initialize the model trainer, and invoke ``train()`` which runs the
training process to return a model.
5. Load some instances you want to run through the model and call
``predict()``.

Schema - schema.yaml
^^^^^^^^^^^^^^^^^^^^

The schema describes the structure of your data. This can be defined
programmatically, but is conveniently expressible in declarative YAML
form, and placed alongside training data.

::

fields:
- name: species
type: discrete
- name: petal_length
type: numeric
- name: petal_width
type: numeric
- name: sepal_length
type: numeric
- name: sepal_width
type: numeric

Metadata - metadata.json
^^^^^^^^^^^^^^^^^^^^^^^^

Metadata is the result of analyzing training data, based on type
information in the schema. Iris is a tiny dataset, so metadata is
readily producable using simple python code looping over the data. For
real-world and large datasets, you'll find Spark and BigQuery (on Google
Cloud Platform) as essential data processing runtimes. Stay tuned -
TensorFX will provide support for these capabilities out of the box.

::

{
"species": { "entries": ["setosa", "virginica", "versicolor"] },
"petal_length": { "min": 4.3, "max": 7.9 },
"petal_width": { "min": 2.0, "max": 4.4 },
"sepal_length": { "min": 1.1, "max": 6.9 },
"sepal_width": { "min": 0.1, "max": 2.5 }
}

Features - features.yaml
^^^^^^^^^^^^^^^^^^^^^^^^

Like schema, features can also be defined programmatically, or expressed
in YAML. Features describe the set of inputs that your models operate
over, and how they are produced by applying transformations to the
fields in your data. These transformations are turned into TensorFlow
graph constructs and applied consistently to both training and
prediction data.

In this particular example, the FeedForwardClassification model requires
two features: X defining the values the model uses for producing
inferences, and Y, the target label that the model is expected to
predict which are defined as follows:

::

features:
- name: X
type: concat
features:
- name: petal_width
type: scale
- name: petal_length
type: scale
- name: sepal_width
type: log
- name: sepal_length
type: log
- name: Y
type: target
fields: species

Running the Model
^^^^^^^^^^^^^^^^^

The python code in the sample can be run directly, or using a ``train``
tool, as shown:

::

python -m tensorfx.tools.train \
--module iris.trainer.main \
--output /tmp/tensorfx/iris/csv \
--data-train iris/data/train.csv \
--data-eval iris/data/eval.csv \
--data-schema iris/data/schema.yaml \
--data-metadata iris/data/metadata.json \
--data-features iris/features.yaml \
--log-level-tensorflow ERROR \
--log-level INFO \
--batch-size 5 \
--max-steps 2000 \
--checkpoint-interval-secs 1 \
--hidden-layers:1 20 \
--hidden-layers:2 10

Once the training is complete, you can list the contents of the output
directory. You should see the model (the prediction graph, and learnt
variables) in the ``model`` subdirectory, alongside checkpoints, and
summaries.

::

ls -R /tmp/tensorfx/iris/csv
checkpoints job.yaml model summaries

/tmp/tensorfx/iris/csv/checkpoints:
checkpoint model.ckpt-2000.index
model.ckpt-1.data-00000-of-00001 model.ckpt-2000.meta
model.ckpt-1.index model.ckpt-2001.data-00000-of-00001
model.ckpt-1.meta model.ckpt-2001.index
model.ckpt-1562.data-00000-of-00001 model.ckpt-2001.meta
model.ckpt-1562.index model.ckpt-778.data-00000-of-00001
model.ckpt-1562.meta model.ckpt-778.index
model.ckpt-2000.data-00000-of-00001 model.ckpt-778.meta

/tmp/tensorfx/iris/csv/model:
saved_model.pb variables

/tmp/tensorfx/iris/csv/model/variables:
variables.data-00000-of-00001 variables.index

/tmp/tensorfx/iris/csv/summaries:
eval prediction train

/tmp/tensorfx/iris/csv/summaries/eval:
events.out.tfevents.1488351760
events.out.tfevents.1488352853

/tmp/tensorfx/iris/csv/summaries/prediction:
events.out.tfevents.1488351765

/tmp/tensorfx/iris/csv/summaries/train:
events.out.tfevents.1488351760
events.out.tfevents.1488352852

Summaries are TensorFlow events logged during training. They can be
observed while the training job is running (which is essential when
running a long or real training job) to understand how your training is
progressing, or how the model is converging (or not!).

::

tensorboard --logdir /tmp/tensorfx/iris/csv

This should bring up TensorBoard. Its useful to see the graph structure,
metrics and other tensors that are automatically published.

**Training Graph**

.. figure:: https://tensorlab.github.io/tensorfx/_static/images/intro-graph.jpg
:alt: Graphs in TensorBoard

Graphs in TensorBoard
**Training Metrics -- Accuracy, Loss and Throughput**

.. figure:: https://tensorlab.github.io/tensorfx/_static/images/intro-metrics.jpg
:alt: Metrics in TensorBoard

Metrics in TensorBoard
**Model Variables -- Weights, Gradients, etc.**

.. figure:: https://tensorlab.github.io/tensorfx/_static/images/intro-watch.jpg
:alt: Watchin Learnt Variables

Watchin Learnt Variables
As you can see, the out-of-box model takes care of a number of details.
The same code can be run on a single machine, or in a cluster (of
course, iris is too simple of a problem to need that).