Logical Functions
These functions provide convenient one-line methods for evaluating expressions. They include methods for checking for empty values, using if-else logic, and implementing switch-case statements among others.
Boolean
Boolean( value ) -> returns: Boolean
Attempts to convert the given non-boolean value to a boolean value. For example a string 'true' would become true.
| Name | Type | Description |
|---|---|---|
| value | String / Number | A text or number value to be converted to a boolean. |
Returns: Boolean
Example
// returns `true`
Boolean('true')
// returns `false`. A value of 1 would return `true`
Boolean(0)
// returns `false`
Boolean('hello')
Decode
Decode( expression, [compare1, return1, ...compareN, returnN]?, default? ) -> returns: *
Evaluates an expression to a value and compares the result value with the value of subsequent parameters. If the expression evaluates to a matching value, it returns the subsequent parameter value. If no matches are found, then a default value may be provided. This is similar to a switch/case statement
| Name | Type | Description |
|---|---|---|
| expression | * | An Arcade expression that must evaluate to a value that can be compared with the provided case values. |
| [compare1, return1, ...compareN, returnN] | * | optional A set of compare values and return value pairs. |
| default | * | optional A default value to return if none of the compare values match. This may be a value of any type. |
Returns:
| Type | Description |
|---|---|
| * | Returns the matched return value. If no matches are found, then the default value is returned. |
Example
// returns a meaningful value when a field contains coded values
var code = $feature.codedValue;
var decodedValue = Decode(code, 1, 'Residential', 2, 'Commercial', 3, 'Mixed', 'Other');
DefaultValue
DefaultValue( value, defaultValue? ) -> returns: *
Replaces an empty value with a provided default value.
| Name | Type | Description |
|---|---|---|
| value | * | The input value to compare against null or ''. This may be a value of any type. However, if this value is an empty array, then the empty array will be returned. |
| defaultValue | * | optional Return this value if the provided value is empty. This may be a value of any type. |
Returns:
| Type | Description |
|---|---|
| * | If value is empty, then the defaultValue is returned. Otherwise, the value of value is returned. This may be a value of any type. |
Example
// If a feature has no value in the POP_2000 field
// then 'no data' is returned
DefaultValue($feature.POP_2000, 'no data')
IIf
IIf( condition, trueValue, falseValue ) -> returns: *
Returns a given value if a conditional expression evaluates to true, and returns an alternate value if that condition evaluates to false.
| Name | Type | Description |
|---|---|---|
| condition | Boolean | A logical expression that must evaluate to true or false. |
| trueValue | * | The value to return if the condition evaluates to true. This may be a value of any type. |
| falseValue | * | The value to return if the condition evaluates to false. This may be a value of any type. |
Returns:
| Type | Description |
|---|---|
| * | If condition is true, then the trueValue is returned. Otherwise, the value of falseValue is returned. |
Example
// returns 'below' if the value is less than 1,000,000.
// if the value is more than 1,000,000, then returns 'above'
var population = $feature.POP_2007;
IIf(population < 1000000, 'below', 'above');
IsEmpty
IsEmpty( value ) -> returns: Boolean
Returns true if the provided value is null or an empty string (e.g. ''). Returns false for all other cases, including empty arrays and dictionaries.
| Name | Type | Description |
|---|---|---|
| value | * | The value that is compared against null or ''. This may be a value of any type. |
Returns: Boolean
Example
// Returns true
IsEmpty(null)
// Returns false
IsEmpty('hello world')
When
When( [expr1, result1, ...exprN, resultN], default ) -> returns: *
Evaluates a series of conditional expressions until one evaluates to true.
| Name | Type | Description |
|---|---|---|
| [expr1, result1, ...exprN, resultN] | * | A series of conditional expressions and return values if the given expression evaluates to true. This may be a value of any type. |
| default | * | Returns this value if all expressions evaluate to false. This may be a value of any type. |
Returns: *
Example
Reclassify a numeric field value to a generic ranking (string)
If all expressions are false, then 'n/a' is returned
var density = $feature.densityField;
var ranking = When(density < 50, 'low', density >=50 && density < 100, 'medium', density >= 100, 'high', 'n/a');
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