Parameters in Rmarkdown Files

Neil Saunders shows how you can parameterize Rmarkdown files, consequently making changes easy later:

The reports follow a common template where the major difference is simply the hashtag. So one way to create these reports is to use the previous one, edit to find/replace the old hashtag with the new one, and save a new file.

That works…but what if we could define the hashtag once, then reuse it programmatically anywhere in the document? Enter Rmarkdown parameters.

The example is small but important.

Building Credit Scorecards

Andre Violante uses SAS to build credit scorecards and analyze credit data:

For this analysis I’m using the SAS Open Source library called SWAT (Scripting Wrapper for Analytics Transfer) to code in Python and execute SAS CAS Action Sets. SWAT acts as a bridge between the python language to CAS Action Sets. CAS Action Sets are synonymous to libraries in Python or packages in R. The one main difference and benefit is that the algorithms within these action sets have been highly parallelized to run on a CAS (Cloud Analytic Services) server. The CAS server is a distributed in-memory engine where I can do all my heavy lifting or computations. The code and Jupyter Notebook are available on GitHub.

Click through for the analysis.

A Functional Approach To PySpark

Tristan Robinson shows us how we can implement a transform function which makes Python code look a little bit more functional:

After a small bit of research I discovered the concept of monkey patching (modifying a program to extend its local execution) the DataFrame object to include a transform function. This function is missing from PySpark but does exist as part of the Scala language already.

The following code can be used to achieve this, and can be stored in a generic wrapper functions notebook to separate it out from your main code. This can then be called to import the functions whenever you need them.

Things which make Python more of a functional language are fine by me. Even though I’d rather use Scala.

Auto ML With SQL Server 2019 Big Data Clusters

Marco Inchiosa has a model scenario for using Big Data Clusters to scale out a machine learning problem:

H2O provides popular open source software for data science and machine learning on big data, including Apache SparkTM integration. It provides two open source python AutoML classes: h2o.automl.H2OAutoML and pysparkling.ml.H2OAutoML. Both APIs use the same underlying algorithm implementations, however, the latter follows the conventions of Apache Spark’s MLlib library and allows you to build machine learning pipelines that include MLlib transformers. We will focus on the latter API in this post.

H2OAutoML supports classification and regression. The ML models built and tuned by H2OAutoML include Random Forests, Gradient Boosting Machines, Deep Neural Nets, Generalized Linear Models, and Stacked Ensembles.

The post only has a few lines of code but there are a lot of working parts under the surface.

Databricks Library Utilities For Notebooks

Srinath Shankar and Todd Greenstein announce a new feature in Databricks Runtime 5.1:

We can see that there are no libraries installed and scoped specifically to this notebook.  Now I’m going to install a later version of SciPy, restart the python interpreter, and then run that same helper function we ran previously to list any libraries installed and scoped specifically to this notebook session. When using the list() function PyPI libraries scoped to this notebook session are displayed as  <library_name>-<version_number>-<repo>, and (empty) indicates that the corresponding part has no specification. This also works with wheel and egg install artifacts, but for the sake of this example we’ll just be installing the single package directly.

This does seem easier than dropping to a shell and installing with Pip, especially if you need different versions of libraries.

Data Science And Data Engineering In HDP 3.0

Saumitra Buragohain, et al, show off some of the things added to the Hortonworks Data Platform for data scientists and data engineers:

We leverage the power of HDP 3.0 from efficient storage (erasure coding), GPU pooling to containerized TensorFlow and Zeppelin to enable this use case. We will the save the details for a different blog (please see the video)- to summarize, as we trained the car on a track, we collected about 30K images with corresponding steering angle data. The training data was stored in a HDP 3.0 cluster and the TensorFlow model was trained using 6 GPU cards and then the model was deployed back on the car. The deep learning use case highlights the combined power of HDP 3.0.

Click through for more additions and demos.

Literate Programming And Notebooks

David Smith sums up a debate on notebooks versus literate programming:

There’s no video yet available of Joel’s talk, but you can guess the theme of that opening slide, and walking through the slides conveys the message well, I think. Yuhui Xie, author and creator of the rmarkdown package, provides a detailed summary and response to Joel’s talk, where he lists Joel’s main critiques of Notebooks:

  1. Hidden state and out-of-order execution

  2. Notebooks are difficult for beginners

  3. Notebooks encourage bad habits

  4. Notebooks discourage modularity and testing

  5. Jupyter’s autocomplete, linting, and way of looking up the help are awkward

  6. Notebooks encourage bad processes

  7. Notebooks hinder reproducible + extensible science

  8. Notebooks make it hard to copy and paste into Slack/Github issues

  9. Errors will always halt execution

  10. Notebooks make it easy to teach poorly

  11. Notebooks make it hard to teach well

Read the whole thing.  I agree with some of these points, but disagree with a few on the list.

Scheduling Jupyter Notebooks

Matthew Seal, et al, explain how they schedule runs of Jupyter notebooks:

On the surface, notebooks pose a lot of challenges: they’re frequently changed, their cell outputs need not match the code, they’re difficult to test, and there’s no easy way to dynamically configure their execution. Furthermore, you need a notebook server to run them, which creates architectural dependencies to facilitate execution. These issues caused some initial push-back internally at the idea. But that has changed as we’ve brought in new tools to our notebook ecosystem.

The biggest game-changer for us is Papermill. Papermill is an nteract library built for configurable and reliable execution of notebooks with production ecosystems in mind. What Papermill does is rather simple. It take a notebook path and some parameter inputs, then executes the requested notebook with the rendered input. As each cell executes, it saves the resulting artifact to an isolated output notebook.

Papermill does look quite interesting.

Using Notebooks At Netflix

Michelle Ufford, et al, explain why and how they use Jupyter Notebooks at Netflix:

Notebooks were first introduced at Netflix to support data science workflows. As their adoption grew among data scientists, we saw an opportunity to scale our tooling efforts. We realized we could leverage the versatility and architecture of Jupyter notebooks and extend it for general data access. In Q3 2017 we began this work in earnest, elevating notebooks from a niche tool to a first-class citizen of the data platform.

From our users’ perspective, notebooks offer a convenient interface for iteratively running code, exploring output, and visualizing data — all from a single cloud-based development environment. We also maintain a Python library that consolidates access to platform APIs. This means users have programmatic access to virtually the entire platform from within a notebook.Because of this combination of versatility, power, and ease of use, we’ve seen rapid organic adoption for all user types across the entire Data Platform.

Today, notebooks are the most popular tool for working with data at Netflix.

Good article.  I love notebooks for two reasons:  pedagogical purposes (it’s easier to show a demo in a notebook) and forcing you to work linearly.

Writing Better Jupyter Notebook Code

Henk Griffioen shows how to write Python code in your IDE of choice and then synchronize a Jupyter Notebook with the results:

How can you get the interactivity back and get our changes immediately in our Notebook? Add %autoreload at the top of your Notebook:

%loadext autoreload # Load the extension%autoreload 2 # Autoreload all modules

%autoreload is a Jupyter extension that reloads modules before executing your code. Functions and classes loaded in notebooks get their functionality updated every time you execute a cell. This means that when new code is saved in the editor, the changes are immediately loaded in your Notebook if you run a cell.

Using %autoreload bridges the gap between Notebook and IDE. You gain all the benefits of an IDE, but you’re still as flexible as before! See the GIF at the top as an example.

That’s a useful trick.  I’ve tended to use notebooks more for post-hoc work, where I’ve already structured my code and want to formalize it for others to use.

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