Using operators in formula expressions - Amazon IoT SiteWise
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Using operators in formula expressions

You can use the following common operators in formula expressions.

Operator Description

+

If both operands are numbers, this operator adds the left and right operands.

If either operand is a string, this operator concatenates the left and right operands as strings. For example, the expression 1 + 2 + " is three" evaluates to "3 is three". The concatenated string can have up to 1024 characters. If the string exceeds 1024 characters, then Amazon IoT SiteWise doesn't output a data point for that computation.

-

Subtracts the right operand from the left operand.

You can only use this operator with numeric operands.

/

Divides the left operand by the right operand.

You can only use this operator with numeric operands.

*

Multiplies the left and right operands.

You can only use this operator with numeric operands.

^

Raises the left operand to the power of the right operand (exponentiation).

You can only use this operator with numeric operands.

%

Returns the remainder from dividing the left operand by the right operand. The result has the same sign as the left operand. This behavior differs from the modulo operation.

You can only use this operator with numeric operands.

x < y

Returns 1 if x is less than y, otherwise 0.

x > y

Returns 1 if x is greater than y, otherwise 0.

x <= y

Returns 1 if x is less than or equal to y, otherwise 0.

x >= y

Returns 1 if x is greater than or equal to y, otherwise 0.

x == y

Returns 1 if x is equal to y, otherwise 0.

x != y

Returns 1 if x is not equal to y, otherwise 0.

!x

Returns 1 if x is evaluated to 0 (false), otherwise 0.

x is evaluated to false if:

  • x is a numeric operand and it's evaluated to 0.

  • x is evaluated to an empty string.

  • x is evaluated to an empty array.

  • x is evaluated to None.

x and y

Returns 0 if x is evaluated to 0 (false). Otherwise, returns the evaluated result of y.

x or y is evaluated to false if:

  • x or y is a numeric operand and it's evaluated to 0.

  • x or y is evaluated to an empty string.

  • x or y is evaluated to an empty array.

  • x or y is evaluated to None.

x or y

Returns 1 if x is evaluated to 1 (true). Otherwise, returns the evaluated result of y.

x or y is evaluated to false if:

  • x or y is a numeric operand and it's evaluated to 0.

  • x or y is evaluated to an empty string.

  • x or y is evaluated to an empty array.

  • x or y is evaluated to None.

not x

Returns 1 if x is evaluated to 0 (false), otherwise 0.

x is evaluated to false if:

  • x is a numeric operand and it's evaluated to 0.

  • x is evaluated to an empty string.

  • x is evaluated to an empty array.

  • x is evaluated to None.

[]

s[index]

Returns the character at an index index of the string s. This is equivalent to the index syntax in Python.

Examples

  • "Hello!"[1] returns e.

  • "Hello!"[-2] returns o.

[]

s[start:end:step]

Returns a slice of the string s. This is equivalent to the slice syntax in Python. This operator has the following arguments:

  • start – (Optional) The inclusive start index of the slice. Defaults to 0.

  • end – (Optional) The exclusive end index of the slice. Defaults to the length of the string.

  • step – (Optional) The number to increment for each step in the slice. For example, you can specify 2 to return a slice with every other character, or specify -1 to reverse the slice. Defaults to 1.

You can omit the step argument to use its default value. For example, s[1:4:1] is equivalent to s[1:4].

The arguments must be integers or the none constant. If you specify none, Amazon IoT SiteWise uses the default value for that argument.

Examples

  • "Hello!"[1:4] returns "ell".

  • "Hello!"[:2] returns "He".

  • "Hello!"[3:] returns "lo!".

  • "Hello!"[:-4] returns "He".

  • "Hello!"[::2] returns "Hlo".

  • "Hello!"[::-1] returns "!olleH".