# Use Arcade expressions with Detect Incidents

There are multiple tools in the GeoAnalytics Tools toolbox that allow you to apply an expression.

GeoAnalytics Tools that use expressions have different usages, as well limitations on which expressions can be applied. At 11.3, all expressions used in ArcGIS GeoAnalytics Server support Arcade.

## Expressions in Detect Incidents

Expressions are used in the Detect Incidents tool to specify start and end conditions for incidents. A Detect Incidents condition must always result in true or false. Use a condition to check if a feature should be included in an incident. The conditions are tested against each feature to determine which features are incidents. Calculations are performed when the analysis runs on your ArcGIS GeoAnalytics Server. Expression examples that you can use are included in the sections below.

## Mathematical operator and function examples

Expressions can mathematically process numbers. The following table shows a sample of available operations.

OperatorExplanationExampleResult

a + b

a plus b.

fieldname contains a value of 1.5.

\$feature["fieldname"] + 2.5

4.0

a - b

a minus b.

fieldname contains a value of 3.3.

\$feature["fieldname"]- 2.2

1.1

a * b

a times b.

fieldname contains a value of 2.0.

\$feature["fieldname"] * 2.2

4.4

a / b

a divided by b.

fieldname contains a value of 4.0.

\$feature["fieldname"] / 1.25

3.2

abs( a )

Returns the absolute (positive) value of a.

fieldname contains a value of -1.5.

abs(\$feature["fieldname"])

1.5

log( a )

Returns the natural logarithm (base E) of a.

fieldname contains a value of 1.

log(\$feature["fieldname"])

0

sin( a )

Returns the trigonometric sine of a. The input is assumed to be an angle in radians.

fieldname contains a value of 1.5707.

sin(\$feature["fieldname"])

1

cos( a )

Returns the trigonometric cosine of a. The input is assumed to be an angle in radians.

fieldname contains a value of 0.

cos(\$feature["fieldname"])

1

tan( a )

Returns the tangent of a. The input is assumed to be an angle in radians.

fieldname contains a value of 0.

tan(\$feature["fieldname"])

0

sqrt( a )

Returns the square root of a.

fieldname contains a value of 9.

sqrt(\$feature["fieldname"])

3

min( a, b )

Returns the lowest-valued number between a and b.

fieldname contains a value of 1.5 and a value of -3.

min(\$feature["fieldname"], -3)

-3

max( a, b )

Returns the highest-valued number between a and b.

fieldname1 contains a value of 1.5, and fieldname2 contains a value of -3.

max(\$feature["fieldname1"], \$feature["fieldname2"])

1.5

constrain(<value>,<low>,<high>)

Returns the input value if it's within the constraining bounds. If the input value is less than the low value, it returns the low value. If the input value is greater than the high value, it returns the high value.

constrain(\$feature["distance"], 0, 10)

constrain(\$feature['Store dist'], 6, distance)

Returns 0 if distance is less than 0, 10 if distance is greater than 10, and distance otherwise.

Returns 6 if Store dist is less than 6, distance if Store dist is greater than distance, and Store dist otherwise.

Multiplication example for a condition detecting an incident.

``\$feature["Distance"] * 2 > 50``

## Text function examples

Detect Incidents expressions can process text. The following table shows a sample of available operations.

OperatorExplanationExampleResult

concatenate( <values>, <separator>)

Concatenates values together and returns a string.

• values—An array of string values to concatenate.
• separator ( optional)—A separator to use for concatenation if the values parameter is an array, or a string to concatenate if a single value is provided for the first parameter. If not provided, it will be empty.

fieldname contains a value of GeoAnalytics.

Concatenate ([\$features["fieldname"], "is", "great!"], ' ')

GeoAnalytics is great!

find(<searchText>, <text>, <startPos>)

Finds a string within a string. Wildcards are not supported.

• searchText—The substring to search for.
• text—The text to search.
• startPos (optional)—The zero-based index of the location in the string to search from.

fieldname1 contains a value of 14NorthStreet and fieldname2 contains a value of North.

find(\$feature["fieldname2"], \$feature["fieldname1"])

2

lower(<value>)

Makes a string lowercase.

• value—The string to be made lowercase.

fieldname contains a value of GEOANALYTICS.

lower(\$feature["fieldname"])

geoanalytics

Text example using find and lower.

``find(("north"), lower("146NorthStreet")) == 2``

## Date function examples

You can use Detect Incidents from expressions that use dates. The following table shows a sample of available operations.

In Arcade, month values range from 0 (January) to 11 (December), days from 1 to 31, hours from 0 (12:00 a.m.) to 23 (11:00 p.m.), minutes and seconds from 0 to 59, and milliseconds from 0 to 999. Arcade dates return time values in the location of your GeoAnalytics Server.

OperatorExplanationExampleResult

date( <value>, <month>, <day>, <hour>, <minute>)

Parses a value or set of values into a date string.

• value(optional)— Either the number of milliseconds since January 1, 1970, UTC or a number representing a year. If a year is specified, the month and day must also be provided in subsequent parameters. This value may also be a date string or an ISO 8601 string to be converted into a date.
• month (optional)—The month (0–11), where 0 is January and 11 is December.
• day (optional)—The day of the month (1–31).
• hour (optional)—The hour of the day (0–23).
• minute (optional)—The minute of the hour (0–59).
• second (optional)—The second of the minute (0–59).
• millisecond (optional)—The millisecond of the second (0–999).

fieldname contains a value of 1476987783555.

Example 1: Date(\$features["fieldname"])

Example 2: Date(2017,0,14,0)

Example 3: Date()

Example 1: 20 Oct 2016 11:23:03 am

Example 2: 14 Jan 2017 12:00:00 am

Example 3: Returns the current time

DateDiff(<date1>, <date2>, <units>)

Subtracts two dates and returns the difference in the specified units.

• date1—The date value from which to subtract a second date.
• date2—The date value to subtract from the first given date.
• units (optional)—The units in which to return the difference of the two given dates. The supported unit types include milliseconds, seconds, minutes, hours, days, months, and years. The default value is milliseconds.

Example 1: DateDiff(Date(2017,1,14,0), Date())

Example 2: DateDiff(Date(2017,1,14,0), Date(), "Years")

Result will vary depending on when you run this command.

Example 1: -20532129137

Example 2: -0.6546783768647119

Year(<dateValue>)

Returns the year of the given date.

• value—A date value from which to get the year.

Example 1: fieldname is a field of type Date with a value of 09 Oct 2017 04:30:43 pm.

Year(\$feature["fieldname"])

Example 2: fieldname is a string field formatted as an ISO 8601 string with a value of 2012-09-27.

Example 1: 2017

Example 2: 2012

## Conditional operators

Conditional statements can use the following operators:

OperatorExplanationExampleResults

a > b

a < b

a is greater than b

a is less than b

10 > 2

False

a >= b

a <= b

a is greater than or equal to b

a is less than or equal to b

abs(-10) >= 10

True

a != b

a is not equal to b

abs(-3) != -3

True

a == b

a is equal to b

abs(-5) == 5

True

<condition1> || <condition2>

Condition 1 or condition 2 is met.

(abs(-5) == 5) || (10 < 2)

True

<condition1> && <condition2>

Condition 1 and condition 2 are met.

(abs(-5) == 5) && (10 < 2)

False

## Logical operator examples

In addition to the conditional operators, you can use more advanced logical operators with Detect Incidents.

FunctionExplanationExampleResult

iif(<condition>,<true value>,<false value>)

Returns one value if a condition evaluates to true, and another value if the condition evaluates to false.

<true value> and <false value> can be the following:

• A numeric field. If there is a space in the field name, use square brackets.
• A number.
• A function.

iif(\$feature["field1"] > \$feature["field2"], \$feature["field1"], 0)

iif(\$feature["field1"] > \$feature["field2"], iif(\$feature["field2"] = 0, \$feature["field3"], \$feature["field4"]), 0)

Returns field1 if field1 is greater than field2, and 0 otherwise.

Returns the result of the second iif function if field1 is greater than field2, and 0 otherwise.

when(<expression1> , <result1> , <expression2> , <result2> , ... , <expressionN> , <resultN>, <default>)

Evaluates a series of expressions in turn until one evaluates to true.

• expression—An expression.
• result—Can be a number or field.
• default—An optional value if none of the expressions match.

when((\$feature["field1"] + 10) > 1, 1,(\$feature["field2"] + 10) > 2 , 2, \$feature["field3"])

If field1 + 10 is greater than 1, it returns 1. If not, it checks if field2 + 10 is greater than 2. If it is, it returns 2. If not, it returns field3.

decode(<conditional val> , <case1> , <result1>, <case2>, <result2>, ... <caseN>, <resultN>, <defaultValue> )

The decode function evaluates an expression and compares its value with subsequent parameters. If the expression matches, it returns the next parameter value. If none match, there is the option for the last parameter to be a default return value.

• conditional val—Can be a field or an expression.
• case—A value to be compared to the conditional val.
• result—The result if the corresponding case matches the conditional val.
• defaultValue—An optional value if no other values are true.

decode(\$feature["field1"] + 3 , \$feature["field1"], 1, \$feature["field2"], 2, 0)

Compares equality between the conditional val field1 + 3 and case1 field1. If true, it returns 1. If false, it compares the equality between field1 + 3 and field2. If true, it returns 2; otherwise, it returns 0.

## Track-aware examples

In addition, some GeoAnalytics Tools, such as Detect Incidents and Calculate Field, can use track-aware equations in Arcade.

FunctionExplanationExampleResult

TrackStartTime()

Calculates the start time of a track in milliseconds from epoch.

Using a track that starts on January 2, 2017.

TrackStartTime()

1483315200000

TrackDuration()

Calculates the duration of a track in milliseconds from the start until the current time step.

Using a track that starts on January 2, 2017, and the current time is January 4, 2017.

TrackDuration()

172800000

TrackCurrentTime()

Calculates the current time in a track.

Using a feature that occurs on January 3, 2017, at 9:00 a.m.

TrackCurrentTime()

1483434000000

TrackIndex

Returns the time index of the feature being calculated.

Calculating this value on the first feature in a track.

TrackIndex

0

TrackFieldWindow(<fieldName>, <startIndex>, <endIndex>)

Returns an array of values in the given field for the specified time index. The window function allows you to go forward and backward in time. The expression is evaluated at each feature in the track.

• The current feature is at index 0.
• Positive values represent features that occur in the future, after the current value. For example, position 1 is the next value in the array.
• Negative numbers represent features that occurred in the past, before the previous feature. For example, -1 is the previous value in the array.

MyField has sequentially ordered values of [10, 20, 30, 40, 50]. The expression is evaluated at each feature in the track. Results are returned inclusive of the start feature, and exclusive of the end feature.

Example 1: TrackFieldWindow("MyField,-1,2)

Example 2: TrackFieldWindow("MyField,-2,0)[0]

Example 3: TrackFieldWindow("MyField,0,3)[2]

Example 1: When evaluated at each feature, the table shows the following results:

 Evaluated feature Result 10 [10,20] 20 [10, 20, 30] 30 [20,30,40] 40 [30,40,50] 50 [40, 50]

Example 2: When evaluated at index 2 (value is 30), it returns 10.

Example 3: When evaluated at index 2 (value is 30), it returns 50.

TrackGeometryWindow(<startIndex>, <endIndex>)

Returns an array of values representing geometry for the specified time index. The window function allows you to go forward and backward in time. The expression is evaluated at each feature in the track.

• The current feature is at index 0.
• Positive values represent features that occur in the future, after the current value. For example, position 1 is the next value in the array.
• Negative numbers represent features that occurred in the past, before the previous feature. For example, -1 is the previous value in the array.

MyField has sequentially ordered values of [10, 20, 30, 40, 50]. The geometry of the features is [{x: 1, y: 1},{x: 2, y: 2} ,{x: null, y: null},{x: 4, y: 4}, {x: 5, y: 5}]. The expression is evaluated at each feature in the track. Results are returned inclusive of the start feature, and exclusive of the end feature.

Example 1: TrackGeometryWindow(-1,2)

Example 2: TrackGeometryWindow(0,1)[0] on a polyline dataset

Example 3: TrackGeometryWindow(0,1)[0] on a polygon dataset

Example 4: Find the X value of the previous point TrackGeometryWindow(-1,0)[0]["x"]

Example 1: When evaluated at each feature, the table shows the following results:

 Evaluated feature Result 10 [{x: 1, y: 1},{x: 2, y: 2}] 20 [{x: 1, y: 1},{x: 2, y: 2} ,{x: null, y: null}] 30 [{x: 2, y: 2} ,{x: null, y: null},{x: 4, y: 4}] 40 [{x: null, y: null},{x: 4, y: 4}, {x: 5, y: 5}] 50 [{x: 4, y: 4}, {x: 5, y: 5}]

Example 2: Polylines are returned in the following format: [{"paths":[[[-180,-22.88],[-177.6,-23.6]],[[180,-18.099999999999994],[179.7,-18.4],[179.4,-18.7],[178.9,-18.9],[178.5,-19.3],[178.2,-19.7],[178.4,-20],[178.8,-20.2],[178.9,-21.8],[179,-22.2],[179.4,-22.7],[180,-22.88]],[[-178,-17],[-178.8,-17.3],[-179.2,-17.5],[-179.6,-17.8],[-179.9,-18],[-180,-18.099999999999994]]]}]

Example 3: Polygons are returned in the following format: [{"rings":[[[-7882559.1197999995,6376090.883500002],[-7893142.474300001,6042715.216800004],[-8544018.775999999,6045361.0554000065],[-8544018.775999999,6376090.883500002],[-7882559.1197999995,6376090.883500002]]]}]

Example 4: Evaluated at index 2 (value is 30): 2

TrackWindow(<value1>, <value2>)

Returns an array of values representing geometry and all attributes for the specified time index. The window function allows you to go forward and backward in time.

• The current feature is at index 0.
• Positive values represent features that occur in the future, after the current value. For example, position 1 is the next value in the array.
• Negative numbers represent features that occurred in the past, before the previous feature. For example, -1 is the previous value in the array.

MyField has sequentially ordered values of [10, 20, 30, 40, 50], in addition to the objectID, globalID and instant_datetime fields. The geometry of the features is [{x: 1, y: 1},{x: 2, y: 2} ,{x: null, y: null},{x: 4, y: 4}, {x: 5, y: 5}]. The expression is evaluated at each feature in the track. Results are returned inclusive of the start feature, and exclusive of the end feature.

Example 1: TrackWindow(-1,0)[0]

Example 2: geometry(TrackWindow(-1,0)[0]["x"]

Example 1: When evaluated at each feature, the table shows the following results:

 Evaluated feature Result 10 20 [{"geometry": {x: 1, y: 1}},{"attributes": {"MyField" : 10, "trackName":"ExampleTrack1"}}] 30 [{"geometry": {x: 2, y: 2}},{"attributes": {"MyField" : 20, "trackName":"ExampleTrack1"}}] 40 [{"geometry": {x: null, y: null}},{"attributes": {"MyField" : 30, "trackName":"ExampleTrack1"}}] 50 [{"geometry": {x: 4, y: 4}},{"attributes": {"MyField" : 40, "trackName":"ExampleTrack1"}}]

Example 2: Evaluated at index 2 (value is 30): 2

Use the following track expressions to calculate distance, speed, and acceleration on tracks.

All distance calculations are calculated in meters, speed in meters per second, and acceleration in meters per second squared. Distances are measured using geodesic distances.

FunctionExplanation

TrackCurrentDistance()

The sum of the distances travelled between observations from the first to the current observation.

TrackDistanceAt(value)

The sum of the distances travelled between observations from the first to the current observation plus the given value.

TrackDistanceWindow(value1, value2)

The distances between the first (inclusive) to the last value (exclusive) in a window about the current observation (0).

TrackCurrentSpeed()

The speed between the previous observation and the current observation.

TrackSpeedAt(value1)

The speed at the observation relative to the current observation. For example, at value 2, it's the speed at the observation two observations after the current observation.

TrackSpeedWindow(value1, value2)

The speed values between the first (inclusive) and the last value (exclusive) in a window around the current observation (0).

TrackCurrentAcceleration()

The acceleration between the previous observation and the current observation.

TrackAccelerationAt(value1)

The acceleration at the observation relative to the current observation.

TrackAccelerationWindow(value1, value2)

The acceleration values between the first (inclusive) to the last value (exclusive) in a window around the current observation (0).

The example calculations for distance, speed, and acceleration will use examples from the following image:

FunctionExample result

TrackCurrentDistance()

Point IDResult (meters)

P1

0

P2

60

P3

80 + 60 = 140

P4

30 + 80 + 60 = 170

P5

35 + 30 + 80 + 60 = 205

P6

25 + 35 + 30 + 80 + 60 = 230

TrackDistanceAt(2)

Point IDResult (meters)

P1

0 + 80 + 60 = 140

P2

30 + 80 + 60 = 170

P3

35 + 30 + 80 + 60 = 205

P4

25 + 35 + 30 + 80 + 60 = 230

P5

null

P6

null

TrackDistanceWindow(-1, 2)

Point IDResult (meters)

P1

[0,60]

P2

[0, 60, 140]

P3

[60, 140, 170]

P4

[140, 170, 205]

P5

[170, 205, 230]

P6

[205, 230]

TrackCurrentSpeed()

Point IDResult (meters/second)

P1

0

P2

60/60

1

P3

80/60

1.33

P4

30/60

.5

P5

35/60

0.5833

P6

25/60

0.4167

TrackSpeedAt(2)

Point IDResult (meters/second)

P1

80/60

1.33

P2

30/60

.5

P3

35/60

0.5833

P4

25/60

0.4167

P5

null

P6

null

TrackSpeedWindow(-1, 2)

Point IDResult (meters/second)

P1

[0, 1]

P2

[0, 1, 1.3]

P3

[1, 1.3, 0.5]

P4

[1.3, 0.5, 0.583]

P5

[0.5, 0.583, -0.4167]

P6

[0.583, -0.4167]

TrackCurrentAcceleration()

Point IDResult (meters/second²)

P1

0

P2

0.0167

P3

0.0056

P4

-0.0014

P5

0.0014

P6

-0.0028

TrackAccelerationAt(2)

Point IDResult (meters/second²)

P1

0.0056

P2

-0.0014

P3

0.0014

P4

-0.0028

P5

null

P6

null

TrackAccelerationWindow(-1, 2)

Point IDResult (meters/second²)

P1

[0, 0.0167]

P2

[0, 0.0167, 0.0056 ]

P3

[0.0167, 0.0056 , -0.0014]

P4

[ 0.0056 , -0.0014, 0.0014]

P5

[-0.0014, 0.0014, -0.0028]

P6

[0.0014, -0.0028]