In order to provide autocomplete suggestions to the user, these suggestions must be identified and stored as phrases that can be searched and returned to the user. This is done by creating an autocomplete dictionary, adding input sources, building the output dictionary, and specifying the dictionary in the display or API.
To create an autocomplete dictionary, click the (
) icon next to the Dictionaries link of the left-side navigation bar. This will
display the New Dictionary screen as shown in Figure 1.

For the purposes of this tutorial, enter autocomplete-tutorial-dictionary into the name field, select base-autocomplete from the Copy defaults from drop down menu, and click on the Add button.
Should Tokenize is disabled. This instructs the Watson Explorer Engine to retain each phrase as a single entry into the dictionary rather than splitting phrases into individual words.
Prune Size is set to 1 because many autocomplete phrases that we want to be able to suggest will be encountered only once in the input. Setting a higher Prune Size could result in a very small autocomplete dictionary but could limit suggestions to common phrases only if your input is noisy.