Ontology widget documentation

doc/widgets/ontology.md

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+Ontology
+========
+
+Generate, edit, load and save ontologies 
+
+**Inputs**
+
+- Words: A table of words.
+
+**Outputs**
+
+- Words: A table of words.
+
+The ontology widget enables various operations with ontologies:
+- Generate ontology from words on the input
+- Load existing ontology from a file or URL
+- Manually edit the ontology
+- Include word from the input in the existing ontology to the position where it fits best according to the embedding similarity
+- Save ontology to file
+
+![](images/Ontology.png)
+
+1. Switch between saved ontologies, add or remove ontology to the library, load or save ontology from/to file.
+2. Browse words from the widget's input, include selected terms automatically in the existing ontology with the `Include` button or grab a word from the list and drop it in the ontology on the right.
+3. (Re)Generate new ontology from all words in the tree on the right.
+4. Set whether the output list includes words in the subtree of selected words even if they are not selected.
+5. Fitness score of current ontology.
+6. Ontology editor and viewer. Drag and drop words to the desired position in the tree, add or remove words with the buttons at the bottom and undo or redo changes. 
+7. Get help, add ontology to the report, or input and output. 
+
+Example
+-------
+
+This example loads the proposals to the government from the URL 
+`http://file.biolab.si/text-semantics/data/proposals-to-government-1k/`, 
+preprocess texts, embedded texts to the vector space with the fastText embedding 
+and shows t-SNE document map. We select a group of documents connected with the 
+property-owning in the document map. Extract Keywords widget extracts keywords 
+of selected subset and sends them to 
+the Ontology widget. In the Ontology widget, we drag words from the Input list 
+to the pane on the right and click the Generate button. After the widget generates 
+the ontology, we can manually perform some minor changes to make ontology even more 
+meaningful.
+
+
+![](images/Ontology-Example.png)