There are multiple tools in the GeoAnalytics Tools toolbox that allow you to apply an expression.
- Buffer expressions in Create Buffers
- Buffer expressions in Reconstruct Tracks
- Join conditions in Join Features
- Incident conditions in Detect Incidents
- Calculating field values in Calculate Field
The GeoAnalytics Tools that use expressions have different usages, as well limitations on which expressions can be applied. At 10.6.1, all expressions used in ArcGIS GeoAnalytics Server support Arcade.
Learn more about Arcade Functions
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 can be used are included in the sections below.
Mathematical operator and function examples
Expressions are able to mathematically process numbers. The following table shows a sample of available operations.
Learn more about mathematical operations and functions available in Arcade
| Operator | Explanation | Example | Result |
|---|---|---|---|
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 or 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.
$feature["Distance"] * 2 > 50Text function examples
Detect Incidents expressions are able to process text. The following table shows a sample of available operations.
Learn more about text functions available in Arcade
| Operator | Explanation | Example | Result |
|---|---|---|---|
concatenate( <values>, <separator>) | Concatenates values together and returns a string.
| fieldname contains a value of GeoAnalytics Concatenate ([$features["fieldname"], "is", "great!"], ' ') | GeoAnalytics is great! |
find(<searchText>, <text>, <startPos>) | Finds a string within a string. Wildcards are not supported.
| fieldname1 contains a value of 14NorthStreet and fieldname2 contains a value of North find($feature["fieldname2"], $feature["fieldname1"]) | 2 |
lower(<value>) | Makes a string lowercase.
| fieldname contains a value of GEOANALYTICS lower($feature["fieldname"]) | geoanalytics |
Text example using find and lower.
find(("north"), lower("146NorthStreet")) == 2Date function examples
You can use Detect Incidents from expressions that use dates. The following table shows a sample of available operations.
Learn more about date functions available in Arcade
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.
| Operator | Explanation | Example | Result |
|---|---|---|---|
date( <value>, <month>, <day>, <hour>, <minute>) | Parses a value or set of values into a date string.
| fieldname contains a value of 1476987783555 Example 1: Date($features["fieldname"]) Example 2: Date(2017,0,14,0) Example 3: Date() | Example 1: 20 Oct 2016 11:23:03 am Example 2: 14 Jan 2017 12:00:00 am Example 3: Returns the current time |
DateDiff(<date1>, <date2>, <units>) | Subtracts two dates, and returns the difference in the specified units.
| Example 1: DateDiff(Date(2017,1,14,0), Date()) Example 2: DateDiff(Date(2017,1,14,0), Date(), "Years") | Result will vary depending on when you run this command. Example 1: -20532129137 Example 2: -0.6546783768647119 |
Year(<dateValue>) | Returns the year of the given date.
| Example 1: fieldname is a field of type Date with a value of 09 Oct 2017 04:30:43 pm Year($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:
| Operator | Explanation | Example | Results |
|---|---|---|---|
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, more advanced logical operators can be used with Detect Incidents.
Learn more about logical functions available in Arcade
| Function | Explanation | Example | Result |
|---|---|---|---|
iff(<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:
| iff($feature["field1"] > $feature["field2"], $feature["field1"], 0) iff($feature["field1"] > $feature["field2"], iff($feature["field2"] = 0, $feature["field3"], $feature["field4"]), 0) | Returns field1 if field1 is greater than field2, and 0 otherwise. Returns the result of the second iff function if field1 is greater than field2, and 0 otherwise. |
when(<expression1> , <result1> , <expression2> , <result2> , ... , <expressionN> , <resultN>, <default>) | Evaluates a series of expressions in turn, until one evaluates to true.
| when(($feature["field1"] + 10) > 1, 1,($feature["field2"] + 10) > 2 , 2, $feature["field3"]) | If field1 + 10 is greater than 1, it returns 1. If not, it checks if field2 + 10 is greater than 2. If it is, it returns 2. If not, it returns field3. |
decode(<conditional val> , <case1> , <result1>, <case2>, <result2>, ... <caseN>, <resultN>, <defaultValue> ) | The decode function evaluates an expression and compares its value with subsequent parameters. If the expression matches, it returns the next parameter value. If none match, there is the option for the last parameter to be a default return value.
| decode($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.
| Function | Explanation | Example | Result | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
$track.field["fieldname"].history(<value1>) | Returns an array of values in the given field for the specified time index.
| MyField has sequentially ordered values of [10, 20, 30, 40, 50, 60, 70, 80]. The value 10 is at index 0, and the value 80 is at index 7. Expressions are evaluated at each index, and examples outline the index being used for the examples. n represents the number of features in the sequence, and k represents the index being evaluated. Example 1:$track.field["MyField"].history(3)) Example 2:$track.field["MyField"].history(-3) Example 3:mean($track.field["MyField"].history(-2)) Example 4:$track.field["MyField"].history(-3)[0] | When example 1 is evaluated at index k, it will return an array of values at index 3 through k. If you evaluate at index 6 (70), an array of the values at index [3, 4, 5, 6] is returned so that the array is [40, 50, 60, 70]. Example 2 returns an array of values calculated as index k minus the given value minus 1 (k-2). If this is evaluated at index 6 (value = 70), the values of k-2, k-1, and k are returned [50, 60, 70]. Example 3 returns the mean of the values at index k-1 and k. If you evaluate this at index 4 (value = 50), you will find the mean of value 50 (index 3) and value 60 (index 4), which equals 65. If you were to evaluate this at index 7, the result would be the mean of 70 and 80, which equals 75. Example 4 returns the first item (index 0) of the array created in example 2, which is 50. | ||||||||||||
$track.field["fieldname"].history(<value1>, <value2>) | Returns an array of values starting from index1 (<value1>) up to index2 (<value2>). | MyField has sequentially ordered values of [10, 20, 30, 40, 50, 60, 70, 80]. 10 is at index 0, and 80 is at index 7. For this example, expressions are evaluated at index 7 (80). Example 1:$track.field["MyField"].history(-3, -2)) Example 2:$track.field["MyField"].history(-5, -2)) | Example 1: [60] Example 2: [40, 50, 60] | ||||||||||||
$track.time.start | Calculates the start time of a track in milliseconds from epoch. | Using a track that starts on January 2, 2017 $track.time.start | 1483315200000 | ||||||||||||
$track.time.duration | 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. $track.time.duration | 172800000 | ||||||||||||
$track.time.current | Calculates the current time in a track. | Using a feature that occurs on January 3, 2017, at 9:00 a.m. $track.time.current | 1483434000000 | ||||||||||||
$track.index | Returns the time index of the feature being calculated. | Calculating this value on the first feature in a track. $track.index | 0 | ||||||||||||
$track.T(<value>, "<units>") | Returns the feature time plus the time created using the numeric <value> and given <units>.
| Using a feature that is at January 2, 2017, at 2 p.m. Example 1: $track.T(1, "hours") Example 2: $track.T(-2, "days") | Example 1: Returns January 2 at 3 p.m.: 1483369200000 Example 2: Returns December 31st at 2 p.m.: 1483192800000 | ||||||||||||
$track.field["fieldname"].window(<value1>, <value2>) | Returns an array of values in the given field for the specified time index. The window function allows you to go forward and backward in time. The expression is evaluated at each feature in the track.
The window function is available at ArcGIS Enterprise 10.6.1. | MyField has sequentially ordered values of [10, 20, 30, 40, 50]. The expression is evaluated at each feature in the track. Results are returned inclusive of the start feature, and exclusive of the end feature. Example 1:$track.field["MyField"].window(-1,2) Example 2:$track.field["MyField"].window(-2,0)[0] Example 3:$track.field["MyField"].window(0,3)[2] | Example 1: When evaluated at each feature, the table shows the following results.
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. | ||||||||||||
$track.geometry.window(<value1>, <value2>) | Returns an array of values representing geometry for the specified time index. The window function allows you to go forward and backward in time. The expression is evaluated at each feature in the track.
The window function is available at ArcGIS Enterprise 10.6.1. | MyField has sequentially ordered values of [10, 20, 30, 40, 50]. The geometry of the features are [{x: 1, y: 1},{x: 2, y: 2} ,{x: null, y: null},{x: 4, y: 4}, {x: 5, y: 5}] The expression is evaluated at each feature in the track. Results are returned inclusive of the start feature, and exclusive of the end feature. Example 1:$track.geometry.window(-1,2) Example 2: $track.geometry.window(0,1)[0] on a polyline dataset Example 3: $track.geometry.window(0,1)[0] on a polygon dataset Example 4: Find the X value of the previous point $track.geometry.window(-1,0)[0]["x"] | Example 1: When evaluated at each feature, the table shows the following results.
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 20): 1 | ||||||||||||
$track.window(<value1>, <value2>) | Returns an array of values representing geometry and all attributes for the specified time index. The window function allows you to go forward and backward in time.
The window function is available at ArcGIS Enterprise 10.6.1. | MyField has sequentially ordered values of [10, 20, 30, 40, 50], in addition to the objectID, globalID and instant_datetime fields. The geometry the features are [{x: 1, y: 1},{x: 2, y: 2} ,{x: null, y: null},{x: 4, y: 4}, {x: 5, y: 5}] The expression is evaluated at each feature in the track. Results are returned inclusive of the start feature, and exclusive of the end feature. Example 1:$track.window(-1,0)[0] Example 2:geometry($track.window(-1,0)[0]["x"] | Example 1: When evaluated at each feature, the table shows the following results.
Example 2: Evaluated at index 2 (value is 20): 1 |