Stream evaluators are different then stream sources or stream decorators. Both stream sources and stream decorators return streams of tuples. Stream evaluators are more like a traditional function that evaluates its parameters and returns an result. That result can be a single value, array, map or other structure.
Stream evaluators can be nested so that the output of an evaluator becomes the input for another evaluator.
Stream evaluators can be called in different contexts. For example a stream evaluator can be called on its own or it can be called within the context of a streaming expression.
abs
The abs function will return the absolute value of the provided single parameter. The abs function will fail to execute if the value is non-numeric. If a null value is found then null will be returned as the result.
abs Parameters
-
Field Name | Raw Number | Number Evaluator
abs Syntax
The expressions below show the various ways in which you can use the abs evaluator. Only one parameter is accepted. Returns a numeric value.
abs(1) // 1, not really a good use case for it
abs(-1) // 1, not really a good use case for it
abs(add(fieldA,fieldB)) // absolute value of fieldA + fieldB
abs(fieldA) // absolute value of fieldAacos
The acos function returns the trigonometric arccosine of a number.
acos Parameters
-
Field Name | Raw Number | Number Evaluator: The value to return the arccosine of.
acos Syntax
acos(100.4) // returns the arccosine of 100.4
acos(fieldA) // returns the arccosine for fieldA.
if(gt(fieldA,fieldB),sin(fieldA),sin(fieldB)) // if fieldA > fieldB then return the arccosine of fieldA, else return the arccosine of fieldBadd
The add function will take 2 or more numeric values and add them together. The add function will fail to execute if any of the values are non-numeric. If a null value is found then null will be returned as the result.
add Parameters
-
Field Name | Raw Number | Number Evaluator -
Field Name | Raw Number | Number Evaluator -
…… -
Field Name | Raw Number | Number Evaluator
add Syntax
The expressions below show the various ways in which you can use the add evaluator. The number and order of these parameters do not matter and is not limited except that at least two parameters are required. Returns a numeric value.
add(1,2,3,4) // 1 + 2 + 3 + 4 == 10
add(1,fieldA) // 1 + value of fieldA
add(fieldA,1.4) // value of fieldA + 1.4
add(fieldA,fieldB,fieldC) // value of fieldA + value of fieldB + value of fieldC
add(fieldA,div(fieldA,fieldB)) // value of fieldA + (value of fieldA / value of fieldB)
add(fieldA,if(gt(fieldA,fieldB),fieldA,fieldB)) // if fieldA > fieldB then fieldA + fieldA, else fieldA + fieldBanalyze
The analyze function analyzes text using a Lucene/Solr analyzer and returns a list of tokens
emitted by the analyzer. The analyze function can be called on its own or within the
select and cartasianProduct Streaming Expressions.
analyze Parameters
-
Field Name|Raw Text: Either the field in a tuple or the raw text to be analyzed. -
Analyzer Field Name: The field name of the analyzer to use to analyze the text.
analyze Syntax
The expressions below show the various ways in which you can use the analyze evaluator.
-
Analyze the raw text:
analyze("hello world", analyzerField) -
Analyze a text field within a
selectexpression. This will annotate the tuples with output of the analyzer:select(expr, analyze(textField, analyzerField) as outField) -
Analyze a text field with a
cartesianProductexpression. This will stream each token emitted by the analyzer in its own tuple:cartesianProduct(expr, analyze(textField, analyzer) as outField)
and
The and function will return the logical AND of at least 2 boolean parameters. The function will fail to execute if any parameters are non-boolean or null. Returns a boolean value.
and Parameters
-
Field Name | Raw Boolean | Boolean Evaluator -
Field Name | Raw Boolean | Boolean Evaluator -
…… -
Field Name | Raw Boolean | Boolean Evaluator
and Syntax
The expressions below show the various ways in which you can use the and evaluator. At least two parameters are required, but there is no limit to how many you can use.
and(true,fieldA) // true && fieldA
and(fieldA,fieldB) // fieldA && fieldB
and(or(fieldA,fieldB),fieldC) // (fieldA || fieldB) && fieldC
and(fieldA,fieldB,fieldC,or(fieldD,fieldE),fieldF)anova
The anova function calculates the analysis of variance for two or more numeric arrays.
anova Parameters
-
numeric array… (two or more)
anova Syntax
anova(numericArray1, numericArray2) // calculates ANOVA for two numeric arrays
anova(numericArray1, numericArray2, numericArray2) // calculates ANOVA for three numeric arraysarray
The array function returns an array of numerics or other objects including other arrays.
array Parameters
-
numeric|array…
array Syntax
array(1, 2, 3) // Array of numerics
array(array(1,2,3), array(4,5,6)) // Array of arraysasin
The asin function returns the trigonometric arcsine of a number.
asin Parameters
-
Field Name | Raw Number | Number Evaluator: The value to return the arcsine of.
asin Syntax
asin(100.4) // returns the sine of 100.4
asine(fieldA) // returns the sine for fieldA.
if(gt(fieldA,fieldB),asin(fieldA),asin(fieldB)) // if fieldA > fieldB then return the asine of fieldA, else return the asine of fieldBatan
The atan function returns the trigonometric arctangent of a number.
atan Parameters
-
Field Name | Raw Number | Number Evaluator: The value to return the arctangent of.
atan Syntax
atan(100.4) // returns the arctangent of 100.4
atan(fieldA) // returns the arctangent for fieldA.
if(gt(fieldA,fieldB),atan(fieldA),atan(fieldB)) // if fieldA > fieldB then return the arctanget of fieldA, else return the arctangent of fieldBcbrt
The cbrt function returns the trigonometric cube root of a number.
cbrt Parameters
-
Field Name | Raw Number | Number Evaluator: The value to return the cube root of.
cbrt Syntax
cbrt(100.4) // returns the square root of 100.4
cbrt(fieldA) // returns the square root for fieldA.
if(gt(fieldA,fieldB),cbrt(fieldA),cbrt(fieldB)) // if fieldA > fieldB then return the cbrt of fieldA, else return the cbrt of fieldBceil
The ceil function rounds a decimal value to the next highest whole number.
ceil Parameters
-
Field Name | Raw Number | Number Evaluator: The decimal to round up.
ceil Syntax
The expressions below show the various ways in which you can use the ceil evaluator.
ceil(100.4) // returns 101.
ceil(fieldA) // returns the next highest whole number for fieldA.
if(gt(fieldA,fieldB),ceil(fieldA),ceil(fieldB)) // if fieldA > fieldB then return the ceil of fieldA, else return the ceil of fieldB.col
The col function returns a numeric array from a list of Tuples. The col
function is used to create numeric arrays from stream sources.
col Parameters
-
list of Tuples -
field name: The field to create the array from.
col Syntax
col(tupleList, fieldName)conv
The conv function returns the convolution of two numeric arrays.
conv Parameters
-
numeric array -
numeric array
conv Syntax
conv(numericArray1, numericArray2)copyOf
The copyOf function creates a copy of a numeric array.
copyOf Parameters
-
numeric array -
length: The length of the copied array. The returned array will be right padded with zeros if the length parameter exceeds the size of the original array.
copyOf Syntax
copyOf(numericArray, length)copyOfRange
The copyOfRange function creates a copy of a range of a numeric array.
copyOfRange Parameters
-
numeric array -
start index -
end index
copyOfRange Syntax
copyOfRange(numericArray, startIndex, endIndex)corr
The corr function returns the Pearson Product Moment Correlation of two numeric arrays.
corr Parameters
-
numeric array -
numeric array
corr Returns
double between -1 and 1
corr Synax
corr(numericArray1, numericArray2)cos
The cos function returns the trigonometric cosine of a number.
cos Parameters
-
Field Name | Raw Number | Number Evaluator: The value to return the hyperbolic cosine of.
cos Syntax
cos(100.4) // returns the arccosine of 100.4
cos(fieldA) // returns the arccosine for fieldA.
if(gt(fieldA,fieldB),cos(fieldA),cos(fieldB)) // if fieldA > fieldB then return the arccosine of fieldA, else return the cosine of fieldBcov
The cov function returns the covariance of two numeric arrays.
cov Parameters
-
numeric array -
numeric array
cov Syntax
cov(numericArray, numericArray)describe
The describe function returns a tuple containing the descriptive statistics for an array.
describe Parameters
-
numeric array
describe Syntax
describe(numericArray)distance
The distance function calculates the Euclidian distance of two numeric arrays.
distance Parameters
-
numeric array -
numeric array
distance Syntax
distance(numericArray1, numuericArray2))div
The div function will take two numeric values and divide them. The function will fail to execute if any of the values are non-numeric or null, or the 2nd value is 0. Returns a numeric value.
div Parameters
-
Field Name | Raw Number | Number Evaluator -
Field Name | Raw Number | Number Evaluator
div Syntax
The expressions below show the various ways in which you can use the div evaluator. The first value will be divided by the second and as such the second cannot be 0.
div(1,2) // 1 / 2
div(1,fieldA) // 1 / fieldA
div(fieldA,1.4) // fieldA / 1.4
div(fieldA,add(fieldA,fieldB)) // fieldA / (fieldA + fieldB)eor
The eor function will return the logical exclusive or of at least two boolean parameters. The function will fail to execute if any parameters are non-boolean or null. Returns a boolean value.
eor Parameters
-
Field Name | Raw Boolean | Boolean Evaluator -
Field Name | Raw Boolean | Boolean Evaluator -
…… -
Field Name | Raw Boolean | Boolean Evaluator
eor Syntax
The expressions below show the various ways in which you can use the eor evaluator. At least two parameters are required, but there is no limit to how many you can use.
eor(true,fieldA) // true iff fieldA is false
eor(fieldA,fieldB) // true iff either fieldA or fieldB is true but not both
eor(eq(fieldA,fieldB),eq(fieldC,fieldD)) // true iff either fieldA == fieldB or fieldC == fieldD but not botheq
The eq function will return whether all the parameters are equal, as per Java’s standard equals(…) function. The function accepts parameters of any type, but will fail to execute if all the parameters are not of the same type. That is, all are Boolean, all are String, all are Numeric. If any any parameters are null and there is at least one parameter that is not null then false will be returned. Returns a boolean value.
eq Parameters
-
Field Name | Raw Value | Evaluator -
Field Name | Raw Value | Evaluator -
…… -
Field Name | Raw Value | Evaluator
eq Syntax
The expressions below show the various ways in which you can use the eq evaluator.
eq(1,2) // 1 == 2
eq(1,fieldA) // 1 == fieldA
eq(fieldA,val(foo)) fieldA == "foo"
eq(add(fieldA,fieldB),6) // fieldA + fieldB == 6finddelay
The finddelay function performs a cross-correlation between two numeric arrays and returns the delay.
finddelay Parameters
-
numeric array -
numeric array
finddelay Syntax
finddelay(numericArray1, numericArray2)floor
The floor function rounds a decimal value to the next lowest whole number.
floor Parameters
-
Field Name | Raw Number | Number Evaluator: The decimal to round down.
floor Syntax
The expressions below show the various ways in which you can use the floor evaluator.
floor(100.4) // returns 100.
ceil(fieldA) // returns the next lowestt whole number for fieldA.
if(gt(fieldA,fieldB),floor(fieldA),floor(fieldB)) // if fieldA > fieldB then return the floor of fieldA, else return the floor of fieldB.gt
The gt function will return whether the first parameter is greater than the second parameter. The function accepts numeric or string parameters, but will fail to execute if all the parameters are not of the same type. That is, all are String or all are Numeric. If any any parameters are null then an error will be raised. Returns a boolean value.
gt Parameters
-
Field Name | Raw Value | Evaluator -
Field Name | Raw Value | Evaluator
gt Syntax
The expressions below show the various ways in which you can use the gt evaluator.
gt(1,2) // 1 > 2
gt(1,fieldA) // 1 > fieldA
gt(fieldA,val(foo)) // fieldA > "foo"
gt(add(fieldA,fieldB),6) // fieldA + fieldB > 6gteq
The gteq function will return whether the first parameter is greater than or equal to the second parameter. The function accepts numeric and string parameters, but will fail to execute if all the parameters are not of the same type. That is, all are String or all are Numeric. If any any parameters are null then an error will be raised. Returns a boolean value.
gteq Parameters
-
Field Name | Raw Value | Evaluator -
Field Name | Raw Value | Evaluator
gteq Syntax
The expressions below show the various ways in which you can use the gteq evaluator.
gteq(1,2) // 1 >= 2
gteq(1,fieldA) // 1 >= fieldA
gteq(fieldA,val(foo)) fieldA >= "foo"
gteq(add(fieldA,fieldB),6) // fieldA + fieldB >= 6hist
The hist function creates a histogram from a numeric array. The hist function is designed
to work with continuous variables.
hist Parameters
-
numeric array -
bins: The number of bins in the histogram. Each returned tuple contains summary statistics for the observations that were within the bin.
hist Sytnax
hist(numericArray, bins)hsin
The hsin function returns the trigonometric hyperbolic sine of a number.
hsin Parameters
-
Field Name | Raw Number | Number Evaluator: The value to return the hyperbolic sine of.
hsin Syntax
hsin(100.4) // returns the hsine of 100.4
hsin(fieldA) // returns the hsine for fieldA.
if(gt(fieldA,fieldB),sin(fieldA),sin(fieldB)) // if fieldA > fieldB then return the hsine of fieldA, else return the hsine of fieldBif
The if function works like a standard conditional if/then statement. If the first parameter is true, then the second parameter will be returned, else the third parameter will be returned. The function accepts a boolean as the first parameter and anything as the second and third parameters. An error will occur if the first parameter is not a boolean or is null.
if Parameters
-
Field Name | Raw Value | Boolean Evaluator -
Field Name | Raw Value | Evaluator -
Field Name | Raw Value | Evaluator
if Syntax
The expressions below show the various ways in which you can use the if evaluator.
if(fieldA,fieldB,fieldC) // if fieldA is true then fieldB else fieldC
if(gt(fieldA,5), fieldA, 5) // if fieldA > 5 then fieldA else 5
if(eq(fieldB,null), null, div(fieldA,fieldB)) // if fieldB is null then null else fieldA / fieldBlength
The length function returns the length of a numeric array.
length Parameters
-
numeric array
length Syntax
length(numericArray)log
The log function will return the natural log of the provided single parameter. The log function will fail to execute if the value is non-numeric. If a null value is found, then null will be returned as the result.
log Parameters
-
Field Name | Raw Number | Number Evaluator
log Syntax
The expressions below show the various ways in which you can use the log evaluator. Only one parameter is accepted. Returns a numeric value.
log(100)
log(add(fieldA,fieldB))
log(fieldA)lt
The lt function will return whether the first parameter is less than the second parameter. The function accepts numeric or string parameters, but will fail to execute if all the parameters are not of the same type. That is, all are String or all are Numeric. If any any parameters are null then an error will be raised. Returns a boolean value.
lt Parameters
-
Field Name | Raw Value | Evaluator -
Field Name | Raw Value | Evaluator
lt Syntax
The expressions below show the various ways in which you can use the lt evaluator.
lt(1,2) // 1 < 2
lt(1,fieldA) // 1 < fieldA
lt(fieldA,val(foo)) fieldA < "foo"
lt(add(fieldA,fieldB),6) // fieldA + fieldB < 6lteq
The lteq function will return whether the first parameter is less than or equal to the second parameter. The function accepts numeric and string parameters, but will fail to execute if all the parameters are not of the same type. That is, all are String or all are Numeric. If any any parameters are null then an error will be raised. Returns a boolean value.
lteq Parameters
-
Field Name | Raw Value | Evaluator -
Field Name | Raw Value | Evaluator
lteq Syntax
The expressions below show the various ways in which you can use the lteq evaluator.
lteq(1,2) // 1 <= 2
lteq(1,fieldA) // 1 <= fieldA
lteq(fieldA,val(foo)) fieldA <= "foo"
lteq(add(fieldA,fieldB),6) // fieldA + fieldB <= 6mod
The mod function returns the remainder (modulo) of the first parameter divided by the second parameter.
mod Parameters
-
Field Name | Raw Number | Number Evaluator: Parameter 1 -
Field Name | Raw Number | Number Evaluator: Parameter 2
mod Syntax
The expressions below show the various ways in which you can use the mod evaluator.
mod(100,3) // returns the remainder of 100 / 3 .
mod(100,fieldA) // returns the remainder of 100 divided by the value of fieldA.
mod(fieldA,1.4) // returns the remainder of fieldA divided by 1.4.
if(gt(fieldA,fieldB),mod(fieldA,fieldB),mod(fieldB,fieldA)) // if fieldA > fieldB then return the remainder of fieldA/fieldB, else return the remainder of fieldB/fieldA.movingAvg
The movingAvg function calculates a moving average over an array of numbers.
movingAvg Parameters
-
numeric array -
window size: The array returned will be smaller than this value.
movingAvg Syntax
movingAverage(numericArray, 30)mult
The mult function will take two or more numeric values and multiply them together. The mult function will fail to execute if any of the values are non-numeric. If a null value is found then null will be returned as the result.
mult Parameters
-
Field Name | Raw Number | Number Evaluator -
Field Name | Raw Number | Number Evaluator -
…… -
Field Name | Raw Number | Number Evaluator
mult Syntax
The expressions below show the various ways in which you can use the mult evaluator. The number and order of these parameters do not matter and is not limited except that at least two parameters are required. Returns a numeric value.
mult(1,2,3,4) // 1 * 2 * 3 * 4
mult(1,fieldA) // 1 * value of fieldA
mult(fieldA,1.4) // value of fieldA * 1.4
mult(fieldA,fieldB,fieldC) // value of fieldA * value of fieldB * value of fieldC
mult(fieldA,div(fieldA,fieldB)) // value of fieldA * (value of fieldA / value of fieldB)
mult(fieldA,if(gt(fieldA,fieldB),fieldA,fieldB)) // if fieldA > fieldB then fieldA * fieldA, else fieldA * fieldBnormalize
The normalize function normalizes a numeric array so that values within the array
have a mean of 0 and standard deviation of 1.
normalize Parameters
-
numeric array
normalize Syntax
normalize(numericArray)not
The not function will return the logical NOT of a single boolean parameter. The function will fail to execute if the parameter is non-boolean or null. Returns a boolean value.
not Parameters
-
Field Name | Raw Boolean | Boolean Evaluator
not Syntax
The expressions below show the various ways in which you can use the not evaluator. Only one parameter is allowed.
not(true) // false
not(fieldA) // true if fieldA is false else false
not(eq(fieldA,fieldB)) // true if fieldA != fieldBor
The or function will return the logical OR of at least 2 boolean parameters. The function will fail to execute if any parameters are non-boolean or null. Returns a boolean value.
or Parameters
-
Field Name | Raw Boolean | Boolean Evaluator -
Field Name | Raw Boolean | Boolean Evaluator -
…… -
Field Name | Raw Boolean | Boolean Evaluator
or Syntax
The expressions below show the various ways in which you can use the or evaluator. At least two parameters are required, but there is no limit to how many you can use.
or(true,fieldA) // true || fieldA
or(fieldA,fieldB) // fieldA || fieldB
or(and(fieldA,fieldB),fieldC) // (fieldA && fieldB) || fieldC
or(fieldA,fieldB,fieldC,and(fieldD,fieldE),fieldF)predict
The predict function predicts the value of an dependent variable based on
the output of the regress function.
predict Parameters
-
regress output -
numeric predictor
predict Syntax
predict(regressOutput, predictor)pow
The pow function returns the value of its first parameter raised to the power of its second parameter.
pow Parameters
-
Field Name | Raw Number | Number Evaluator: Parameter 1 -
Field Name | Raw Number | Number Evaluator: Parameter 2
pow Syntax
The expressions below show the various ways in which you can use the pow evaluator.
pow(2,3) // returns 2 raised to the 3rd power.
pow(4,fieldA) // returns 4 raised by the value of fieldA.
pow(fieldA,1.4) // returns the value of fieldA raised by 1.4.
if(gt(fieldA,fieldB),pow(fieldA,fieldB),pow(fieldB,fieldA)) // if fieldA > fieldB then raise fieldA by fieldB, else raise fieldB by fieldA.rank
The rank performs a rank transformation on a numeric array.
rank Parameters
-
numeric array
rank Syntax
rank(numericArray)raw
The raw function will return whatever raw value is the parameter. This is useful for cases where you want to use a string as part of another evaluator.
raw Parameters
-
Raw Value
raw Syntax
The expressions below show the various ways in which you can use the raw evaluator. Whatever is inside will be returned as-is. Internal evaluators are considered strings and are not evaluated.
raw(foo) // "foo"
raw(count(*)) // "count(*)"
raw(45) // 45
raw(true) // "true" (note: this returns the string "true" and not the boolean true)
eq(raw(fieldA), fieldA) // true if the value of fieldA equals the string "fieldA"regress
The regress function performs a simple regression on two numeric arrays.
The result of this expression is also used by the predict function.
regress Parameters
-
numeric array -
numeric array
regress Syntax
regress(numericArray1, numericArray2)rev
The rev function reverses the order of a numeric array.
rev Parameters
-
numeric array
rev Syntax
rev(numericArray)round
The round function returns the closest whole number to the argument
round Parameters
-
Field Name | Raw Number | Number Evaluator: The value to return the square root of.
round Syntax
round(100.4)
round(fieldA)
if(gt(fieldA,fieldB),sqrt(fieldA),sqrt(fieldB)) // if fieldA > fieldB then return the round of fieldA, else return the round of fieldBscale
The scale function multiplies all the elements of an array by a number.
scale Parameters
-
number -
numeric array
scale Syntax
scale(number, numericArray)sequence
The sequence function returns an array of numbers based on its parameters.
sequence Parameters
-
length -
start -
stride
sequence Syntax
sequence(100, 0, 1) // Returns a sequence of length 100, starting from 0 with a stride of 1.sin
The sin function returns the trigonometric sine of a number.
sin Parameters
-
Field Name | Raw Number | Number Evaluator: The value to return the sine of.
sin Syntax
sin(100.4) // returns the sine of 100.4
sine(fieldA) // returns the sine for fieldA.
if(gt(fieldA,fieldB),sin(fieldA),sin(fieldB)) // if fieldA > fieldB then return the sine of fieldA, else return the sine of fieldBsqrt
The sqrt function returns the trigonometric square root of a number.
sqrt Parameters
-
Field Name | Raw Number | Number Evaluator: The value to return the square root of.
sqrt Syntax
sqrt(100.4) // returns the square root of 100.4
sqrt(fieldA) // returns the square root for fieldA.
if(gt(fieldA,fieldB),sqrt(fieldA),sqrt(fieldB)) // if fieldA > fieldB then return the sqrt of fieldA, else return the sqrt of fieldBsub
The sub function will take 2 or more numeric values and subtract them, from left to right. The sub function will fail to execute if any of the values are non-numeric. If a null value is found then null will be returned as the result.
sub Parameters
-
Field Name | Raw Number | Number Evaluator -
Field Name | Raw Number | Number Evaluator -
…… -
Field Name | Raw Number | Number Evaluator
sub Syntax
The expressions below show the various ways in which you can use the sub evaluator. The number of these parameters does not matter and is not limited except that at least two parameters are required. Returns a numeric value.
sub(1,2,3,4) // 1 - 2 - 3 - 4
sub(1,fieldA) // 1 - value of fieldA
sub(fieldA,1.4) // value of fieldA - 1.4
sub(fieldA,fieldB,fieldC) // value of fieldA - value of fieldB - value of fieldC
sub(fieldA,div(fieldA,fieldB)) // value of fieldA - (value of fieldA / value of fieldB)
if(gt(fieldA,fieldB),sub(fieldA,fieldB),sub(fieldB,fieldA)) // if fieldA > fieldB then fieldA - fieldB, else fieldB - field
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