NOTE

Panopticon Streams also supports nullability where:

·         a field may or may not allow null/empty/missing/NA values.

·         functions or operators may or may not allow null arguments (e.g., you can’t divide seven by null).

Aggregation Function

Description

Example

Nullability

avg(X)

Average of a field across records.

avg(numericField)

a

collect(X)

Returns last n values of a field across records.

collect(fieldName,valuesCount)

Parameters:

·         fieldName – Field name whose last n values should be retained.

·         valuesCount – Number of values to be retained.

collect(symbol,3)

a

count(X)

Counts the number of records.

count()

delta(X)

Returns the difference of the last and second last value of the integer field.

delta(numericField)

a

first(X)

First value of a field.

first(fieldName)

a

firstNonNull(X)

First non-null value of a field.

firstNonNull(fieldName)

a

last(X)

Last value of a field.

last(fieldName)

a

lastNonNull(X)

Last non-null value of a field.

lastNonNull(fieldName)

a

max(X)

Maximum of an integer field across records.

max(fieldName)

a

min(X)

Minimum of an integer field across records.

min(fieldName)

a

prev(X)

Previous values of a field record.

prev(fieldName)

a

samples(X)

Count of non-null values of field records.

samples(fieldName)

a

sdevp(X)

Returns the standard deviation of an entire population.

sdevp(numericField)

a

sdevs(X)

Estimates standard deviation based on a sample.

sdevs(numericField)

a

sum(X)

Sums a field across records.

sum(numericField)

a

varp(X)

Returns the variance in an entire population.

varp(numericField)

a

vars(X)

Returns the variance based on a sample.

vars(numericField)

a

wavg(X)

Weighted average of a field across records.

wavg(score,weight)

Parameters:

·         score – Numeric field for score.

·         weight – Numeric field for weightage.

wavg(marks,weight)

a

  NOTE

The following aggregates work with a time window (can subtract): count, samples, sum, sdev, var, and avg