Neural Network Poetry
As you may know, April is national poetry month, an annual series of events by the Academy of American Poets to help support the appreciation of American poetry. If you’re looking for great book-length collections of poems, you might be interested in the Iowa Poetry Prize winners. Many of the previous years’ winners are made available in PDF form at Iowa Research Online. What you may not know is that April is also National Poetry Generation Month, an annual tradition where programmers and creative coders spend the month writing code that generates poetry.
In honor of this time of year, I thought I’d take a look at the Iowa Poetry Prize winners through code. There are many methods for analyzing and generating natural language, but one system that has received a lot of attention recently is neural networks. A neural network is a large collection of artificial neurons based very loosely on a biological brain. These neurons exist in layers that perform statistical calculations and affect the state of other connected neurons. It differs from other computational models in that there is no knowledge hard coded and controlled by elaborate conditional statements (if this then that). Rather, neural networks learn to solve tasks by observing data and producing optimal functions that will produce similar outputs given new data it’s never seen before. The uses for such a system include image and speech recognition, classification problems, and many forms of prediction and decision making. For example, a neural net could be trained to detect images of cats by observing tens of thousands of labeled images of cats. Google has recently launched a new project that uses this technique to match your doodles with professional drawings.
What happens when we train an artificial intelligence to write english language having only read Iowa Poetry Prize winners? Let’s find out!
To start, I downloaded all of the IPP winners from Iowa Research Online, extracted the poems as plain text, and concatenated them all into a single text file named poems.txt. This served as the training set. Next, I set up this Torch-based Docker container implementation of a recurrent neural network based on work by Andrej Karpathy and Justin Johnson. It was tempting to spin up the Google cloud VM with an attached GPU, since these types of machine learning tasks are sped up greatly running on a graphics processing unit with CUDA, but it’s also quite expensive at 75 cents-per-hour. Once I had it working, I started the preprocessing and training, which took about 16 hours to complete.
After a lot of experimentation to create some useful training models and keep the network from overfitting and underfitting the data, I had something that was acceptable and so began sampling output. One parameter of sampling that was fun to play with was the “temperature” of the sample. A lower temperature produced output that was much more predictable and less error prone while a higher temperature was much more inventive but riddled with mistakes. I decided to split the difference and start at 0.5. Here’s the first poem.
Speritas Of The Stars
Morning comes of the sun
to the thin world is a star of her light.
The sheet and the body of parts
of the flame is a light, the body
sees of the wars beautiful on the street.
The sun, the stars of the sound, and desire,
and a man could love the streets.
The single shiller of light,
and the single stranger falls countal.
Father and she were the sutters of the body
instraining to the complete
window of light, still.
You’ll notice a few words in this poem that don’t actually exist in english. That’s because this RNN operates at the character level, not the word level. It has to learn, from scratch, how to write english. It starts with random strings of letters and slowly, after many iterations, learns about spaces, proper punctuation, and finally readable words. The higher the sampling temperature, the more invented words. Let’s look at a “hot” poem.
Pelies, One Yighter
The shadows just plance croved
I am one
its funlet from the wind
staskaccus, gring of detches of hearts face eashog
what wing to the streed in the resert of change, a glince
She read on his fill bathered, a hand the
with beautiful, casty, stery, kooms, in one father
something the mouth cold leaves.
A night and no one is a woman; you green her
My spere would must not the look teering mower
I see itselfor.
At that sign they thought the remelled the mum,
but like an wait they mite of ammiral
after things of the body
which children would love
the forest flowers and hark a path.
The shawr rate in a ruched parts in humstily
his poom her as of the trabs conterlity.
Much more Jabberwockyesque. If we ease up just a little on this we get
A Badicar Flower
The watcher blue says
they would have shapes,
the night dreaming,
a painted nother
tricks me, the wind,
the dayed from the boging feeling
of the histance in his everyness.
What do you think — poetry prize worthy? While writing poetry is fun, there are, of course, practical applications too. I’m currently working with faculty member Mariola Espinosa on a HathiTrust project called Fighting Fever in the Caribbean: Medicine and Empire, 1650-1902. We have 9.3 million pages of medical journals and need to find references to yellow fever in multiple languages. A trained neural network could look through these quickly and find references that a human might miss. I’m also working on another project with Heidi Renee Aijala looking for references to coal smoke in Victorian literature. Perhaps a neural net could be trained to look for non-keyword references.
While I’m probably not going to put a poet out of work any time soon, you can imagine many real-world uses. There is a tremendous potential for neural networks and other types of machine learning to caption images, transcribe handwriting, translate documents, understand the spoken word, and play chess at the international master level. Perhaps someday it might also write a meaningful poem.