8e. Tutorial

Question 1

What was the AIRbnb review topic about?

Answer 1

500 reviews, downloaded by lecturer

Question 2

What happens in the first step?

Answer 2

File is opened - all airbnb reviews

Question 3

Why does this step happen (step 2)?

Answer 3

A numeric column like 12345 is treated by KNIME as a number for calculations, not as text to tokenize or parse.

Converting it with Number to String turns it into textual content that text-mining nodes can consume. KNIME’s Number to String node is specifically for converting number columns into strings.

Question 4

What does this node do? (+ why?)

Answer 4

Strings to Document turns plain text in a table into KNIME’s document type for text processing.

Why?: in KNIME text mining, a document column is the standard input type for many downstream text nodes. For example, Sentence Extractor works on a document and returns its sentences, and KNIME’s stemming/text-preprocessing nodes describe operating on terms contained in an input

Question 5

What does this node do?

Answer 5

• removes all words that have less than 3 characters (“a”)
  -> because usually not really meaningful

Question 6

What does this node do?

Answer 6

Topic extraction!

-> chooses set amount of topics and number of words
-> calculates a weighing per topic
-> assigns to greatest weighted topic