List of Available Lens Functions

Owned by Russ Waterson (Unlicensed)
Last updated: Sept 26, 2024 by Russell Waterson
10 min read

The information in this document refers to functions that are available in the latest version of the RML Mapper feature.
Lenses may require updating in order to take advantage of any newly created functions.

 

 

General Functionality

  • A triple will not be generated if the subject or object is provided will a NULL value.

  • Strings passed into functions may be sourced from

    • References (The entire value of a field in the source document)

    • Templates (A string that includes values of fields in the source document, as well as manually specified strings)

    • Outputs from other Functions (Functions may therefore be nested)

Prefixes

In order to make use of the below functions, you must include the following prefixes in your mapping files:

@prefix fnml: <http://semweb.mmlab.be/ns/fnml#> . @prefix fno: <https://w3id.org/function/ontology#> . @prefix grel: <http://users.ugent.be/~bjdmeest/function/grel.ttl#> .

Custom Data Lens Functions

ifEqual

  • Description: If a value equals and expected value, return if else that

  • Required Parameters:

    • Input - Input text

    • String1 - Value to be equal to

    • String2 - If equal return this value

    • String3 - If not equal return this value

  • Returns: String3 if input equals String1, otherwise return String2

fnml:functionValue [ # The object is the result of the function rr:predicateObjectMap [ rr:predicate fno:executes ; # Execute the function rr:objectMap [ rr:constant grel:removeEqualValues ] # The name of the function ] ; rr:predicateObjectMap [ rr:predicate grel:valueParameter ; # Expected input type rr:objectMap [ rr:template "{Name}" ] # Input value param, referenced from the data source ] ; rr:predicateObjectMap [ rr:predicate grel:valueParameter2 ; # Expected input type rr:objectMap [ rr:template "John" ] # Input value param, string constant as defined in "" ] ; rr:predicateObjectMap [ rr:predicate grel:valueParameter3 ; # Expected input type rr:objectMap [ rr:template "matches name" ] # Input value param, string constant as defined in "" ] ; rr:predicateObjectMap [ rr:predicate grel:valueParameter4 ; # Expected input type rr:objectMap [ rr:template "no match" ] # Input value param, string constant as defined in "" ] ; ]

toPascalCase

  • Description: Returns as value as PascalCase

  • Required Parameters:

    • Input - Input text

  • Returns: Input as PascalCase

fnml:functionValue [ # The object is the result of the function rr:predicateObjectMap [ rr:predicate fno:executes ; # Execute the function rr:objectMap [ rr:constant grel:toPascalCase ] # The name of the function ] ; rr:predicateObjectMap [ rr:predicate grel:valueParameter ; # Expected input type rr:objectMap [ rml:reference "Name" ] # Input value param, referenced from the data source ] ]

toCamelCase

  • Description: Returns as value as camelCase

  • Required Parameters:

    • Input - Input text

  • Returns: Input as camelCase

toKebabCase

  • Description: Returns as value as kebab-case

  • Required Parameters:

    • Input - Input text

  • Returns: Input as kebab-case

toScreamingSnakeCase

  • Description: Returns as value as SCREAMING_SNAKE_CASE

  • Required Parameters:

    • Input - Input text

  • Returns: Input as SCREAMING_SNAKE_CASE

toSnakeCase

  • Description: Returns as value as snake_case

  • Required Parameters:

    • Input - Input text

  • Returns: Input as snake_case

unixEpochConverter

  • Description: Reads a long representing unix time to xsd:date

  • Required Parameters:

    • Input - Input text

    • String1 - days, seconds, milliseconds (default)

  • Returns: a unix time conversion

existsThen

  • Description: Takes an input value and if it is not null, return the output value

  • Required Parameters:

    • Input - Input text

    • String1 - value to return when not null

  • Returns: String1 when not null, otherwise null

removeEqualValues

  • Description: Returns NULL if Input is equal to any of the values in String1

  • Use Case: Don’t generate a triple if the value in the source data is ‘None’ or N/A

  • Required Parameters:

    • Input - Input text

    • String1 - Delimited list of values

  • Returns: Input or NULL

findAndReplace

  • Description: Find part or all of the first input value from a list of regex, provided by the second input of comma separated values, and replace with its respective value from the third input of comma separated values

  • Use Case: Remove undesirable values from within field data.

  • Expects:

    • Input - Input text

    • String1 - Regex find values

    • String2 - Regex replace values

  • Returns: Input, where matched values from String1 are replaced with corresponding values from String2

removeAllDoubleQuotes

  • Description: Returns the input with all double quotes removed

  • Use Case: Remove unnecessary double quotation marks from within field data.

  • Expects:

    • Input- Input text

  • Returns: Input with all double quotation marks have been removed.

translateToISODate

  • Description: Allows valid xsd:date values to be generated from non ISO standard date formats.

  • Use Case: The source data provides a date, but it’s not in xsd:date format.

  • Expects:

    • YearString - Delimited list containing

      • Input - Input text

      • StartPosition - Which position to start from, relative to the beginning on the Input text

      • CharacterCount - Number of characters after the StartPosition to extract

      • Prefix -2 digit prefix to add to extracted 2 character date, to make a 4 character date.

    • MonthString - Delimited list containing

      • Input - Input text

      • StartPosition - Which position to start from, relative to the beginning on the Input text

      • CharacterCount - Number of characters after the StartPosition to extract

    • DayString - Delimited list containing

      • Input - Input text

      • StartPosition - Which position to start from, relative to the beginning on the Input text

      • CharacterCount - Number of characters after the StartPosition to extract

  • Returns: Date in the format YYYY-MM-DD

extractCharactersFromEnd

  • Description: Extract a configurable number of characters from within a provided string, relative to the end of the string.

  • Use Case: You only want the last 5 characters from a provided string.

  • Expects:

    • Input - Input text

    • String1 - Which position to start from, relative to the end on the Input text (0 being the last character)

    • String2 - Number of characters prior to the position in String1 to extract

  • Returns: A slice of characters from the input text or NULL

extractCharactersFromStart

  • Description: Extract a configurable number of characters from within a provided string, relative to the beginning of the string.

  • Use Case: You only want the first 5 characters from a provided string.

  • Expects:

    • Input - Input text

    • String1 - Which position to start from, relative to the beginning of the Input text (0 being the first character)

    • String2 - Number of characters after the position in String1 to extract

  • Returns: A slice of characters from the input text or NULL

retrieveValueFromDelimitedList

  • Description: Extracts a specified value from a provided delimited list.

  • Use Case:

  • Expects:

    • Input - Input delimited list

    • String1 - Value used as the delimiter

    • String2 - Which element from the delimited list to return

  • Returns: An element extract from the Input list, or NULL

toUpperCase

  • Description: Converts a provided string to UPPERCASE

  • Use Case:

  • Expects:

    • Input

  • Returns: Input, in UPPERCASE

toLowerCase

  • Description: Converts a provided string to lowercase

  • Use Case:

  • Expects:

    • Input

  • Returns: Input, in lowercase

concat

  • Description: Combines 2 provided strings, into 1 string

  • Use Case:

  • Expects:

    • Input1

    • Input2

  • Returns: Input1Input2

random

  • Description: Returns a randomly generated UUID

  • Use Case:

  • Expects: None

  • Returns: A randomly generated UUID

toUpperCaseURL

  • Description: Ensures that a provided string is a URL, and converts it to one if it isn’t (Prepends HTTP:// where necessary),

  • Use Case:

  • Expects:

    • Input

  • Returns: Input1 in UPPERCASE converted to a URL

 

 

Default Mapper Functions

DBpedia Spotlight annotate

Returns the DBpedia URLs of the detected entities in the input text

Function IRI: http://example.com/idlab/function/dbpediaSpotlight

Read local file as string

Returns the content of a local file as string

Function IRI: http://example.com/idlab/function/readFile

Label

IRI

Label

IRI

input path

http://example.com/idlab/function/path

True condition

Returns the value if the given boolean is true, else null

Function IRI: http://example.com/idlab/function/trueCondition

decide

Returns a given value if input is equal to another given value

Function IRI: http://example.com/idlab/function/decide

getMIMEType

Returns the MIME Type of a filename

Function IRI: http://example.com/idlab/function/getMIMEType

Label

IRI

Label

IRI

input string

http://example.com/idlab/function/str

listContainsElement

Returns true if the string is found in the list

Function IRI: http://example.com/idlab/function/listContainsElement

random

Returns a random uuid.

Function IRI: http://example.com/idlab/function/random

This function does not take any arguments.

stringContainsOtherString

Returns true if a string is found in a delimited string.

Function IRI: http://example.com/idlab/function/stringContainsOtherString

toLowercase

Returns the input with all letters in lower case.

Function IRI: http://users.ugent.be/~bjdmeest/function/grel.ttl#toLowerCase

toUppercase

Returns the input with all letters in upper case.

Function IRI: http://users.ugent.be/~bjdmeest/function/grel.ttl#toUpperCase

toUpperCaseURL

Returns an uppercase, valid url.

Function IRI: http://example.com/idlab/function/toUpperCaseURL

Label

IRI

Label

IRI

input string

http://example.com/idlab/function/str