How to Create a Term Document Matrix

This article describes how to go from a table of text:

To a state where a term document matrix represents the words in the text as a table (or matrix) of numbers:

Requirements

A verbatim text variable that contains sentences or phrases. Text variables are represented by a small a next to the variable in the Data Sets tree:

Method

1. Create a table by dragging a text variable onto a Page.
2. From the toolbar, go to Anything > Advanced Analysis > Text Analysis > Advanced > Setup Text Analysis.
3. From the object inspector, select the text variable in the Inputs > Text Analysis Options > Text variable drop-down or drag the text variable from your Data Sets tree into the Text variable field.
4. Make any modifications to the options in your text analysis setup as described in How to Set Up Your Text Analysis.
5. Go to Anything > Advanced Analysis > Text Analysis > Advanced > Term Document Matrix.
6. From the object inspector > Inputs > Setup item, select your text analysis output that was created in Steps 3-4.
7. OPTIONAL: Update Minimum document count as needed based on your text analysis.
8. Go to Calculation > Custom code.
9. Paste the following code into the R CODE box:

library(tm)
non.sparse.matrix <- as.matrix(term.document.matrix)

In the code above, replace term.document.matrix with the name of the output that was created in step 6. You can find this by selecting the object and going to Properties > GENERAL > Name.

See Also

How to Create a Sparse Matrix

How to Set Up Your Text Analysis

How to Hook Up a Term Document Matrix to Custom R Code