Entering values or using a field are not the only way you can specify the size of a buffer using GeoAnalytics Tools. In some cases, you might want to perform a mathematical calculation to set the buffer size. You can perform simple as well as advanced calculations that are applied to all records. This calculation is applied to each feature. The sections below include examples of using a buffer expression. Calculations are performed when analysis is run on your ArcGIS GeoAnalytics Server.

At ArcGIS Enterprise 10.6 and later, expressions are formatted using Arcade Expressions. Learn more about Arcade expressions and about Arcade Expressions with GeoAnalytics Server and 10.6 and later.

Buffer expressions are used by the Reconstruct Tracks and Create Buffers tools.

## Simple calculations

### Simple math examples

Buffer expressions are able to mathematically process numbers.

Operator | Explanation | Example | Result |
---|---|---|---|

a + b | a plus b | fieldname contains a value of 1.5 ["fieldname"] + 2.5 | 4.0 |

a - b | a minus b | fieldname contains a value of 3.3 ["fieldname"]- 2.2 | 1.1 |

a * b | a multiplied by b | fieldname contains a value of 2.0 ["fieldname"] * 2.2 | 4.4 |

a / b | a divided by b | fieldname contains a value of 4.0 ["fieldname"] / 1.25 | 3.2 |

abs( a ) | Returns the absolute (positive) value of a. | fieldname contains a value of -1.5 abs(["fieldname"]) | 1.5 |

log ( a ) | Returns the natural logarithm (base E) of a. | fieldname contains a value of 1 log(["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(["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(["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(["fieldname"]) | 0 |

sqrt( a ) | Returns the square root of a. | fieldname contains a value of 9 sqrt(["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(["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(["fieldname1"], ["fieldname2"]) | 1.5 |

Multiplication

`["Distance"] * 2`

## Built-in functions for GeoAnalytics Tools

### As distance function examples

Buffer expressions are able to cast numeric values to a linear distance.

Function | Explanation | Example | Result |
---|---|---|---|

as_meters( <value> ) | Applies a calculation assuming the input values are in meters | as_meters( ["fieldname"] ) as_meters(150) | Results are buffered by 150 meters. |

as_kilometers( <value> ) | Applies a calculation assuming the input values are in kilometers | as_kilometers( ["fieldname"] ) as_kilometers(150) | Results are buffered by 150 kilometers. |

as_feet( <value> ) | Applies a calculation assuming the input values are in feet | as_feet( ["fieldname"] ) as_feet(150) | Results are buffered by 150 feet. |

as_yards( <value> ) | Applies a calculation assuming the input values are in yards | as_yards( ["fieldname"] ) as_yards(150) | Results are buffered by 150 yards. |

as_nautical_miles( <value> ) | Applies a calculation assuming the input values are in nautical miles | as_nautical_miles( ["fieldname"] ) as_nautical_miles(150) | Results are buffered by 150 nautical miles. |

as_miles( <value> ) | Applies a calculation assuming the input values are in miles | as_miles( ["fieldname"] ) as_miles(150) | Results are buffered by 150 miles. |

For each feature, multiply the field Distance assuming it's in kilometers, and add 10 meters.

`as_kilometers(["Distance"]) + as_meters(10)`

### Advanced build in functions for GeoAnalytics Tools buffer expressions

In addition to simple mathematical expressions, more advanced functions can be used to apply buffer expressions.

Function | Explanation | Example | Result |
---|---|---|---|

constrain(<value>,<low>,<high>) | Returns the input value if it's within the constraining bounds. If the value is less than the low value, it returns the low value. If the value is greater than the high value, it returns the high value. | constrain( ["distance"], 0, 10) constrain(['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. |

iff(<condition>,<true value>,<false value>) | Returns one value if a condition evaluates to true, and another value if that 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.
| iff(["field1"] > ["field2"], ["field1"], 0) iff(["field1"] > ["field2"], iff(["field2"] = 0, ["field3"], ["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. - expression—An expression.
- result—Can be a number or field.
- default—An optional value if none of the expression match.
| when((["field1"] + 10) > 1, 1,(["field2"] + 10) > 2 , 2, ["field3"]) | If field1 + 10 is greater than 1, returns 1. If not, checks if field2 + 10 is greater than 2. If yes, 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(["field1"] + 3 , ["field1"], 1, ["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. |

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> OR <condition2> | Condition one or condition two is met. | (abs(-5) == 5) OR (10 < 2) | True |

<condition1> AND <condition2> | Condition one and condition two are met. | (abs(-5) == 5) AND (10 < 2) | False |