7.00.02 - Output - Aster Analytics

Teradata Aster® Analytics Foundation User GuideUpdate 2

Aster Analytics
Release Number
September 2017
Content Type
Programming Reference
User Guide
Publication ID
English (United States)
Last Update
The LDATrainer function outputs:
  • Message
  • Model table
  • [Optional] Output table
LDATrainer Output Message Schema
Column Name Data Type Description
message TEXT, VARCHAR, or VARCHAR(n) Reports the iteration steps and perplexity of the model.

The perplexity formula is:

perplexity = 2 H (p) = 2 x p (x) log2 p (x)

where H (p) is the entropy of the distribution.

Perplexity varies with training documents. However, you can use perplexity to find the best model for a specified set of training documents: Generate models for several subsets of the training documents and then choose the model with the lowest perplexity.

LDATrainer Model Table Schema
Column Name Data Type Description
topicid INTEGER Internally generated topic identifier.
value BYTEA Model in binary format.
LDATrainer Output Table Schema
Column Name Data Type Description
docid Same as data type of doc_column in input table Contains document identifiers from the input table.
topicid INTEGER Contains topic identifiers from the model table.
topicweight DOUBLE PRECISION Contains topic weights.
topicwords TEXT, VARCHAR, or VARCHAR(n) Optional. Contains topic words, separated by commas.
The model table is in BYTEA format, which is not readable. To see the binary contents, use the function LDATopicPrinter.