Entities

Entities are important pieces of information that can be extracted from an expression. You want to store these entities as variables so you can re-use them later on.

Types of entities

There are four types of entities:

  • Match entity: if the user states a word that is part of a predefined list or matches a certain pattern, this word will be detected as a match entity. For example: "I want to know more about the Premium pack" β†’ @product: Premium

  • Contextual entity: train your NLP so it can recognise entities that depend on the context of an expression. For example: "Book a train ticket from Brussels to Amsterdam" β†’ @origin: Brussels, @destination: Amsterdam

  • System entity: these are entities that are pre-built into the platform and can be detected automatically. For example: "My e-mail address is [email protected]" β†’ @sys.email: [email protected]

  • Composite entity: a combination of different, but related entities For example: "Two fries please" β†’ @order consists of @sys.number (2) and @foodItem (fries)

When to use which entity type?

Use this handy flowchart so you can find out which type of entity best fits your use case:

Click the image to enlarge it

All entities will only be detected after you've updated the NLP at least once

1 – Match entities

Match entities are a type of entity that is detected when the user states a word that is part of a predefined list, or matches a certain pattern.

Option 1: Match text

Create a list of possible values for an entity. If a user mentions one of these values during their conversation with the bot, that value will automatically be saved as an entity.

For example: you have defined @product as a match entity, and have created three possible values: Basic, Intermediate, Premium. When a user says "I want to know more about the Premium pack", the entity @product will be saved, with the value "Premium".

Match entities are case insensitive.

Synonyms

For each value, you can add a synonym that will be detected as the original value. Synonyms allow you to add alternatives to entities that are assigned to the same value.

For example:

I want to go to Brussels

I want to go to Bruxelles

The meaning of the two expressions above is exactly the same, but you want to convert Bruxelles to Brussels so your bot can work with one and the same value.

Option 2: Match pattern

Use a pattern to extract data from a user expression if it matches a particular format. Patterns are formed as regular expressions (like in Python). You can learn more about how to create regular expressions here.

For example: you have defined @customerID as a match entity, and have provided the following regex pattern: [a-z]{5}[0-9]{2}. This means that when a users says "My customer ID is terwf33", which consists of 5 letters and 2 numbers, it is saved as @customerID with the value "terwf33".

Find a concrete example of how to use match entities below πŸ‘‡

2 – Contextual entities

Contextual entities use machine learning to identify entities in sentences by learning which type of word your entity is, where it's placed in the sentence, and what the specific context is.

​Synonyms can also be added for contextual entities.

Contextual entities are the only type of entities that can (and should be) added to the expression itself, for example: "I want to book a train ticket from @origin to @destination"

You can see a live example of how you can use contextual entities in our tutorial here:

Fuzzy matching for contextual entities

Fuzzy matching allows you to recognise a slight variation of an entity value (or its synonym) as the original value. For example "Brusselt" will be automatically corrected to "Brussels" by using fuzzy matching.

Fuzzy matching is quite strict. Less than 20% of the characters are allowed to be different in order to link it to another entity. This is to avoid that the value is linked to another entity which also has overlap.

3 – System entities

System entities are entities that can be automatically extracted from the user's messages. You can use these to enrich your conversations and data integrations without having to configure custom entities yourself.

You should not overwrite System Entities yourself – they will automatically be overwritten with the last detected value (if any are available). So instead, copy the System Entity variable to a variable of your own choosing outside the sys or internal namespaces.

Supported system entities

Chatlayer.ai supports the following system entity types:

Variable name

Example input by user

Example result in session

sys.email

"[email protected]"

sys: {email: '[email protected]'}

sys.phone_number

"+32 487 23 02 03"

sys: {phone_number: '(+32) 487230203'}

sys.ordinal

"5th"

sys: {ordinal: '5'}

sys.amount_of_money

"5 euro"

sys: {amount_of money: '5', amount_of_money_currency: 'EUR'}

sys.distance

"5 kilometers"

sys: {distance: '5', distance_unit: 'kilometre'}

sys.number

"eighty eight"

sys: {number: '88'}

sys.quantity

"3 liters"

sys: {quantity: '3', quantity_unit: 'litre'}

sys.temperature

"80C"

sys: {temperature '80', temperature_unit: 'celsius'

sys.time

"3 pm tomorrow"

sys: {time: '2020-12-25T15:00:00.000+00:00', time_grain: 'hour'}

sys.url

"www.chatlayer.ai/jobs"

sys: {url: 'www.chatlayer.ai/jobs', url_domain: 'chatlayer.ai'}

sys.duration

"3 hours"

sys: {duration: '3', duration_unit: 'hour', duration_normalized: '10800', duration_normalized_unit: 'second'}

4 – Composite entities

A Composite Entity is a combination of different, but related entities. This type of entity allows you to combine two separate entities into a single one.

For example: "Two fries please": @order (composite entity) consists of @sys.number: 2 (system entity) and @foodItem: fries (match entity)

The difference between entities, variables, and values

A value is a possible element of a variable or entity. For example, the variable 'destination' can have the following values: Antwerp, London, Brussels, ...

An entity that was successfully recognized by the NLP engine will be stored as a variable. For example, say you created the match text entity 'Levels' with values 'Beginner', 'Intermediate' and 'Expert'. When the user says 'I think I'm an expert', the value 'expert' will be saved as a variable. So a variable is an entity that was successfully recognized and stored by the chatbot.

Variables are pieces of information you know about the person talking to the bot. For example, if someone is talking to the bot in English, we will remember their preference and save 'English' as a value for the variable β€œLanguage”. Variables and values always appear in pairs. They are stored on the user session that gathers all information about a user.

Entities should only be used if their value is needed in the bot conversations. For example, if your bot can help the user find information about a certain product and you need the name of that product to look up the information in a database, you should use entities. If your bot simply redirects to a web page with an overview of all products, you do not need entities.

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