Lambda Expressions

This is archived documentation for InfluxData product versions that are no longer maintained. For newer documentation, see the latest InfluxData documentation.

TICKscript uses lambda expressions to define transformations on data points as well as define boolean conditions that act as filters. TICKscript tries to be similar to InfluxQL in that most expressions that you would use in an InfluxQL WHERE clause will work as expressions in TICKscript. There are few exceptions:

  • All field or tag identifiers must be double quoted.
  • The comparison operator for equality is == not =.

All expressions in TICKscript begin with the lambda: keyword.

.where(lambda: "host" == '')


These lambda expressions are stateful, meaning that each time they are evaluated internal state can change and will persist until the next evaluation. This may seem odd as part of an expression language but it has a powerful use case. You can define a function within the language that is essentially a online/streaming algorithm and with each call the function state is updated. For example the built-in function sigma that calculates a running mean and standard deviation and returns the number of standard deviations the current data point is away from the mean.


sigma("value") > 3

Each time that the expression is evaluated the new value it updates the running statistics and then returns the deviation. This simple expression evaluates to false while the stream of data points it has received remains within 3 standard deviations of the running mean. As soon as a value is processed that is more than 3 standard deviation it evaluates to true. Now you can use that expression inside of a TICKscript to define powerful alerts.

TICKscript with lambda expression:

        // use an expression to define when an alert should go critical.
.crit(lambda: sigma("value") > 3)

Builtin Functions


Converts a string into a boolean via Go’s strconv.ParseBool

bool(value string) bool


Converts a string or float64 into an int64 via Go’s strconv.ParseInt or simple float64() coercion. Strings are assumed to be decimal numbers.

int(value float64 or string) int64


Converts a string or int64 into an float64 via Go’s strconv.ParseFloat or simple int64() coercion.

float(value int64 or string) float64


Computes the number of standard deviations a given value is away from the running mean. Each time the expression is evaluated the running mean and standard deviation are updated.

sigma(value float64) float64


Count takes no arguments but returns the number of times the expression has been evaluated.

count() int64

Time functions

Within each expression the time field contains the time of the current data point. The following functions can be used on the time field. Each function returns an int64.

minutethe minute within the hour: range [0,59]
hourthe hour within the day: range [0,23]
weekdaythe weekday within the week: range [0,6] 0 is Sunday
daythe day within the month: range [1,31]
monththe month within the year: range [1,12]
yearthe year

Example usage:

lambda: hour("time") == 9

The above expression evaluates to true if the hour of the day for the data point is 9 AM, using local time.

Math functions

The following mathematical functions are available. Each function is implemented via the equivalent Go function. Short descriptions are provided here but see the Go docs for more details.

absAbs returns the absolute value of x.
acosAcos returns the arccosine, in radians, of x.
acoshAcosh returns the inverse hyperbolic cosine of x.
asinAsin returns the arcsine, in radians, of x.
asinhAsinh returns the inverse hyperbolic sine of x.
atanAtan returns the arctangent, in radians, of x.
atan2Atan2 returns the arc tangent of y/x, using the signs of the two to determine the quadrant of the return value.
atanhAtanh returns the inverse hyperbolic tangent of x.
cbrtCbrt returns the cube root of x.
ceilCeil returns the least integer value greater than or equal to x.
cosCos returns the cosine of the radian argument x.
coshCosh returns the hyperbolic cosine of x.
erfErf returns the error function of x.
erfcErfc returns the complementary error function of x.
expExp returns e**x, the base-e exponential of x.
exp2Exp2 returns 2**x, the base-2 exponential of x.
expm1Expm1 returns e**x - 1, the base-e exponential of x minus 1. It is more accurate than Exp(x) - 1 when x is near zero.
floorFloor returns the greatest integer value less than or equal to x.
gammaGamma returns the Gamma function of x.
hypotHypot returns Sqrt(p*p + q*q), taking care to avoid unnecessary overflow and underflow.
j0J0 returns the order-zero Bessel function of the first kind.
j1J1 returns the order-one Bessel function of the first kind.
jnJn returns the order-n Bessel function of the first kind.
logLog returns the natural logarithm of x.
log10Log10 returns the decimal logarithm of x.
log1pLog1p returns the natural logarithm of 1 plus its argument x. It is more accurate than Log(1 + x) when x is near zero.
log2Log2 returns the binary logarithm of x.
logbLogb returns the binary exponent of x.
maxMax returns the larger of x or y.
minMin returns the smaller of x or y.
modMod returns the floating-point remainder of x/y. The magnitude of the result is less than y and its sign agrees with that of x.
powPow returns x**y, the base-x exponential of y.
pow10Pow10 returns 10**e, the base-10 exponential of e.
sinSin returns the sine of the radian argument x.
sinhSinh returns the hyperbolic sine of x.
sqrtSqrt returns the square root of x.
tanTan returns the tangent of the radian argument x.
tanhTanh returns the hyperbolic tangent of x.
truncTrunc returns the integer value of x.
y0Y0 returns the order-zero Bessel function of the second kind.
y1Y1 returns the order-one Bessel function of the second kind.
ynYn returns the order-n Bessel function of the second kind.