Topic Words in Context (TWiC) Close Reading
Table of Contents
- How to Use
- Example HTML Files
- Technical Notes & Known Issues
TWiC Close Reading (TCR) is a Python script that generates interactive HTML files for texts that have been modeled by the MALLET topic modeler. It leans on code and ideas from my previous D3 visualization for topic models, "Topic Words in Context" or "TWiC", which offers a more comprehensive look at topic models. TCR is built to look at the texts themselves under the lens of the topic weights in each text, and topic word weights in their topics. While TWiC already provides a similar view in its "Text View" panel, TCR is meant to give a more lightweight, more informative and easily browsable version of this view. The idea here is to facilitate making substantive connections between a human-authored text and the underlying statistical data that models it. Below is a sample image so you can get an idea of what such a view looks like. Here it is visited on one of the last paragraphs of Herman Melville's Moby-Dick (spoiler alert).
The Modeled Text
In the view above of a single text considered by the topic model, topics - and thus the words from them - are each given a unique color. On the left is a view of the full text with those colored words. (Really a topic model considers each text as a "bag" of words without order, but here we reinstitute the human-authored ordering for context.) Just scroll down to see more of the text. Mousing over each word will highlight it and any other instance of that word in the text in white. This will also result in any other word from the topic of that word to be highlighted in gray. Corresponding words in the composite rank word list on the right are also highlighted. This portion of the view is explained below. (Note: Some browsing of the text and composite rank word list may be necessary to find all related topic words.)
On the bottom is a view of the output model data with one additional metric. This information is supplied as one mouses over topic words:
1. Topic word
2. Top 20 words of that topic (ranked by their topic-word weight)
3. Document-Topic Rank
4. Topic-Word Rank
5. Composite Rank (of both document-topic and topic-word weights for this word in this text)
As one might expect, listed values include the topic word being highlighted and the top 20 words from that word's topic. Also listed, however, are the rankings of three weights that, given the context of the output topic model, can help viewers understand the place of these words in that model.
Since documents of the topic model receive an apportionment or distribution of topics weighted by the modeling process, we are able to rank the most highly weighted/most featured topics of the document. This is one way of perceiving topics in a text.
Topics themselves, each of which are composed of all words in the modeled corpus, also receive an apportionment or distribution of word weight. Ranking words in a topic by this weight is yet another way of perceiving how a topic model is represented at the level of a single text.
The composite rank takes into account both of these weights and how (when multiplied together into a composite weight) they compare to other composite weights of words in this text. Among the many ways to attempt a close examination of the topic model when juxtaposed like this with a human-authored ordering a text in that model, the composite rank is supplied as one suggestion of how to weigh the relevance or likelihood of strong/weak word associations in the model.
Topic Words ordered by Composite Rank
On the right is a list of all of the words in the text ordered by the composite rank (see the description just above this section). Multiple instances of words are included and are given the same rank. Listed next to each word in parentheses are their document-topic rank and topic-word rank. These topic words also highlight upon mouseover in the same way they do for the text. Mousing over the words will also highlight corresponding words from this topic in the text on the left. Scrolling down will reveal more of this list. NOTE: You will notice that composite, document-topic, and/or topic-word rankings are sometimes strikingly the same for a string of topic words listed in the composite rank panel. This is not a bug. For topics with near-nil probability within documents and topic words with near-nil probability within topics, a very low dummy weight is assigned. This has the effect of producing the similarly ranked topic words.
How to Use
Using TWiC Close Reading (TCR) is a simple, two-step process:
1. Edit the script's YAML configuration file in the root folder,
2. Run TCR's primary Python script,
YAML Configuration File
The folder where your MALLET topic model files sit. All of the files listed below are required for TWiC Close Reading (TCR) to function. TCR supports model files from MALLET version 2.0.8 and higher.
Name of the (unzipped) topic "state" file generated by the MALLET option
Name of the file generated by the
--output-doc-topics MALLET option that contains corpus file names and their respective topic weights.
Name of the file generated by the
--output-topic-keys MALLET option that contains the numeric topic ID, average corpus weight for each topic, and the familiar list of its top 20 topic words.
Name of the file generated by the
--topic-word-weights-file MALLET option that contains a list of words, their assigned topic ID, and weight in that topic.
The folder where the txt files of your corpus modeled by MALLET are stored
The folder where you would like TCR to output its HTML files
A name for your corpus used internally by TCR. Will only be shown in its terminal output. (Please use underscores in lieu of spaces).
Once you have filled in all the fields in
tcr_config.yaml, just run TWiC Close Reading's primary Python script:
python twic_close_reading.py. (Note: This script does rely on a few other Python scripts stored in the
lib folder, so you do need to leave it in place in the root folder of TCR.)
Example HTML Files
Example HTML files generated by TWiC Close Reading from a topic model of the paragraphs of Herman Melville's Moby-Dick; or, The Whale, Bartleby, the Scrivener: A Story of Wall Street, Pierre; or, The Ambiguities, and Billy Budd, Sailor are included in the folder
data/output/example. (Just a few HTML files are given. The entire modeled corpus is just under 5,000 files.)
Technical Notes & Known Issues
- TWiC Close Reading (TCR) is compatible with MALLET versions 2.0.8 and higher
- Please be aware that for some texts, MALLET may not produce state file data. If no state file data is detected for a text, TCR will not produce an HTML file for it since that data is an integral part of its output. A file,
tcr_unprocessed.txt, will be output into TCR's root folder listing the text files which did not have an HTML file produced for them.
- Expected text encoding is UTF-8
- TCR should be functional across MacOS, Windows, and Linux. Its Python script detects and uses the appropriate folder separator character. However, there is currently no support for the
\r\ncombined carriage return + linefeed character.