# Installing GPU version of TensorFlow™ for use in R on Windows

The other night I got TensorFlow™ (TF) and Keras-based text classifier in R to successfully run on my gaming PC that has Windows 10 and an NVIDIA GeForce GTX 980 graphics card, so I figured I'd write up a full walkthrough, since I had to make minor detours and the official instructions assume -- in my opinion -- a certain level of knowledge that might make the process inaccessible to some folks.

Why would you want to install and use the GPU version of TF? "TensorFlow programs typically run significantly faster on a GPU than on a CPU." Graphics processing units (GPUs) are typically used to render 3D graphics for video games. As a result of the race for real-time rendering of more and more realistic-looking scenes, they have gotten really good at performing vector/matrix operations and linear algebra. While CPUs are still better for general purpose computing and there is some overhead in transferring data to/from the GPU's memory, GPUs are a more powerful resource for performing those particular calculations.

Notes: For installing on Ubuntu, you can follow RStudio's instructions. If you're interested in a Python-only (sans R) installation on Linux, follow NVIDIA's instructions.

# Prerequisites

• An NVIDIA GPU with CUDA Compute Capability 3.0 or higher. Check your GPU's compute capability here. For more details, refer to Requirements to run TensorFlow with GPU support.
• For example, I like using Microsoft R Open (MRO) on my gaming PC with a multi-core CPU because MRO includes and links to the multi-threaded Intel Math Kernel Library (MKL), which parallelizes vector/matrix operations.
• I also recommend installing and using the RStudio IDE.
• You will need devtools: install.packages("devtools", repos = c(CRAN = "https://cran.rstudio.com"))
• Python 3.5 (required for TF at the time of writing) via Anaconda (recommended):
1. Install Anaconda3 (in my case it was Anaconda3 4.4.0), which will install Python 3.6 (at the time of writing) but we'll take care of that.
2. Add Anaconda3 and Anaconda3/Scripts to your PATH environment variable so that python.exe and pip.exe could be found, in case you did not check that option during the installation process. (See these instructions for how to do that.)
3. Install Python 3.5 by opening up the Anaconda Prompt (look for it in the Anaconda folder in the Start menu) and running conda install python=3.5
4. Verify by running python --version

# Setting Up

## CUDA & cuDNN

1. Presumably you've got the latest NVIDIA drivers.
2. Install CUDA Toolkit 8.0 (or later).
3. Download and extract CUDA Deep Neural Network library (cuDNN) v5.1 (specifically), which requires signing up for a free NVIDIA Developer account.
4. Add the path to the bin directory (where the DLL is) to the PATH system environment variable. (See these instructions for how to do that.) For example, mine is C:\cudnn-8.0\bin

## TF & Keras in R

Once you've got R, Python 3.5, CUDA, and cuDNN installed and configured:

1. You may need to install the dev version of the processx package: devtools::install_github("r-lib/processx") because everything installed OK for me originally but when I ran devtools::update_packages() it gave me an error about processx missing, so I'm including this optional step.
2. Install reticulate package for interfacing with Python in R: devtools::install_github("rstudio/reticulate")
3. Install tensorflow package: devtools::install_github("rstudio/tensorflow")
4. Install GPU version of TF (see this page for more details):
library(tensorflow)
install_tensorflow(gpu = TRUE)
5. Verify by running:
use_condaenv("r-tensorflow")
sess = tf$Session() hello <- tf$constant('Hello, TensorFlow!')
sess\$run(hello)
6. Install keras package: devtools::install_github("rstudio/keras")

You should be able to run RStudio's examples now.

Hope this helps! :D

# Probabilistic programming languages for statistical inference

This post was inspired by a question about JAGS vs BUGS vs Stan:

Explaining the differences would be too much for Twitter, so I'm just gonna give a quick explanation here.

# BUGS (Bayesian inference Using Gibbs Sampling)

I was taught to do Bayesian stats using WinBUGS, which is now a very outdated (but stable) piece of software for Windows. There's also OpenBUGS, an open source version that can run on Macs and Linux PCs. Benefits include: academic papers and textbooks written in 80s, 90s, and early 2000s that use Bayesian stats might include models written in BUGS. For example, Bayesian Data Analysis (1st and 2nd editions) and Data Analysis Using Regression and Multilevel/Hierarchical Models use BUGS.

# JAGS (Just Another Gibbs Sampler)

JAGS, like OpenBUGS, is available across multiple different platforms. The language it uses is basically BUGS, but with a few minor differences that require you to rewrite BUGS models to JAGS before you can run them.

I used JAGS during my time at University of Pittsburgh's neuropsych research program because we used Macs, I liked that JAGS was written from scratch, and I preferred the R interface to JAGS over the R interfaces to WinBUGS/OpenBUGS.

# Stan

Stan is a newcomer and it's pretty awesome. It has a bunch of interfaces to modern data analysis tools. The language syntax was designed from scratch by people who wrote BUGS programs and thought it could be better and were inspired by R's vectorized functions. It's strict about the type of data (integer vs real number) and about parameters vs transformed parameters, which might make it harder to get into than BUGS which gives you a lot of leeway (kind of like R does), but I personally like constraints and precision since that's what allows it to be hella fast. Stan is fast because it compiles your Stan models into C++ (hence the need for strictness). I also really like Stan's Shiny app for exploring the posterior samples, which also supports MCMC output from JAGS and others.

The latest (3rd) edition of Bayesian Data Analysis has examples in Stan and Statistical Rethinking uses R and Stan, so if you're using modern textbooks to learn Bayesian statistics, you're more likely to find examples in Stan.

There are two pretty cool R interfaces to Stan that make it easier to specify your models. The first one is rethinking (accompanies the Statistical Rethinking book I linked to earlier) and then there's brms, which uses a formula syntax similar to lme4.

Stan has an active discussion board and development, so if you run into issues with a particular model or distribution, or if you're trying to do something that Stan doesn't support, you can reach out there and you'll receive help and maybe they'll even add support for whatever it is that you were trying to do.

# Mostly-free resources for learning data science

In the past year or two I've had several friends approach me about learning statistics because their employer/organization was moving toward a more data-driven approach to decision making. (This brought me a lot of joy.) I firmly believe you don't actually need a fancy degree and tens of thousands of dollars in tuition debt to be able to engage with data, glean insights, and make inferences from it. And now, thanks to many wonderful statisticians on the Internet, there is now a plethora of freely accessible resources that enable curious minds to learn the art and science of statistics.

First, I recommend installing R and RStudio for actually using it. They're free and what I use for almost all of my statistical analyses. Most of the links in this post involve learning by doing statistics in R.

Okay, now on to learning stats…

There's Data Analysis and Statistical Inference + interactive companion course by Mine Çetinkaya-Rundel (Duke University). She has also written the OpenIntro to Statistics book (available for free as a PDF).

Free, self-paced online courses from trustworthy institutions:

Not free online courses from trustworthy institutions:

Free books and other resources:

Book recommendations:

• Introductory Statistics with R by Peter Dalgaard
• Doing Data Science: Straight Talk from the Frontline by Cathy O'Neil
• Statistics in a Nutshell by Sarah Boslaugh
• Principles of Uncertainty by Jay Kadane (free PDF at http://uncertainty.stat.cmu.edu/)
• Statistical Rethinking: A Bayesian Course with Examples in R and Stan by Richard McElreath

Phew! Okay, that should be enough. Feel free to suggest more in the comments below.