Package dev.morphia.aggregation.expressions

Class WindowExpressions

java.lang.Object

dev.morphia.aggregation.expressions.WindowExpressions

public final class WindowExpressions
extends Object

Provides window specific operations.

Since:

2.3

Method Summary

Modifier and Type	Method	Description
static Expression	covariancePop(Expression first, Expression second)	Returns the population covariance of two numeric expressions that are evaluated using documents in the $setWindowFields stage window.
static Expression	covarianceSamp(Expression first, Expression second)	Returns the sample covariance of two numeric expressions that are evaluated using documents in the $setWindowFields stage window.
static Expression	denseRank()	Returns the document position (known as the rank) relative to other documents in the $setWindowFields stage partition.
static CalculusExpression	derivative(Expression input)	Returns the average rate of change within the specified window.
static Expression	documentNumber()	Returns the position of a document (known as the document number) in the $setWindowFields stage partition.
static Expression	expMovingAvg(Expression input, int n)	Returns the exponential moving average of numeric expressions applied to documents in a partition defined in the $setWindowFields stage.
static CalculusExpression	integral(Expression input)	Returns the approximation of the area under a curve, which is calculated using the trapezoidal rule where each set of adjacent documents form a trapezoid using the:
static Expression	linearFill(Expression fillValue)	Fills null and missing fields in a window using linear interpolation based on surrounding field values.
static Expression	locf(Expression fillValue)	Last observation carried forward.
static Expression	rank()	Returns the document position (known as the rank) relative to other documents in the $setWindowFields stage partition.
static ShiftExpression	shift(Expression output, long by, Expression defaultValue)	Returns the value from an expression applied to a document in a specified position relative to the current document in the $setWindowFields stage partition.
static Expression	stdDevPop(Expression value, Expression... additional)	Returns the population standard deviation of the input values.
static Expression	stdDevSamp(Expression value, Expression... additional)	Returns the sample standard deviation of the input values.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

covariancePop

public static Expression covariancePop(Expression first,
                                       Expression second)

Returns the population covariance of two numeric expressions that are evaluated using documents in the $setWindowFields stage window.

$covariancePop is only available in the $setWindowFields stage.

Parameters:

first - the first expression to evaluate

second - the second expression to evaluate

Returns:

the new expression

Since:

2.3

See Also:

Aggregation.setWindowFields(SetWindowFields)

Since server release

5.0

MongoDB documentation

Aggregration Expression: $covariancePop

covarianceSamp

public static Expression covarianceSamp(Expression first,
                                        Expression second)

Returns the sample covariance of two numeric expressions that are evaluated using documents in the $setWindowFields stage window.

$covarianceSamp is only available in the $setWindowFields stage.

Parameters:

first - the first expression to evaluate

second - the second expression to evaluate

Returns:

the new expression

Since:

2.3

See Also:

Aggregation.setWindowFields(SetWindowFields)

Since server release

5.0

MongoDB documentation

Aggregration Expression: $covarianceSamp

denseRank

public static Expression denseRank()

Returns the document position (known as the rank) relative to other documents in the $setWindowFields stage partition.

Returns:

the expression

Since:

2.3

Since server release

5.0

MongoDB documentation

Aggregration Expression: $denseRank

derivative

public static CalculusExpression derivative(Expression input)

Returns the average rate of change within the specified window.

Parameters:

input - Specifies the expression to evaluate. The expression must evaluate to a number.

Returns:

the new expression

Since:

2.3

Since server release

5.0

MongoDB documentation

Aggregration Expression: $derivative

documentNumber

public static Expression documentNumber()

Returns the position of a document (known as the document number) in the $setWindowFields stage partition.

Returns:

the new expression

Since:

2.3

See Also:

Aggregation.setWindowFields(SetWindowFields)

Since server release

5.0

MongoDB documentation

Aggregration Expression: $documentNumber

expMovingAvg

public static Expression expMovingAvg(Expression input,
                                      int n)

Returns the exponential moving average of numeric expressions applied to documents in a partition defined in the $setWindowFields stage.

$expMovingAvg is only available in the $setWindowFields stage.

Parameters:

input - Specifies the expression to evaluate. Non-numeric expressions are ignored.

n - An integer that specifies the number of historical documents that have a significant mathematical weight in the exponential moving average calculation, with the most recent documents contributing the most weight.

Returns:

the new expression

Since:

2.3

See Also:

Aggregation.setWindowFields(SetWindowFields)

Since server release

5.0

MongoDB documentation

Aggregration Expression: $expMovingAvg

integral

public static CalculusExpression integral(Expression input)

Returns the approximation of the area under a curve, which is calculated using the trapezoidal rule where each set of adjacent documents form a trapezoid using the:

Parameters:

input - Specifies the expression to evaluate. The expression must evaluate to a number.

Returns:

the new expression

Since:

2.3

Since server release

5.0

MongoDB documentation

Aggregration Expression: $integral

linearFill

public static Expression linearFill(Expression fillValue)

Fills null and missing fields in a window using linear interpolation based on surrounding field values.

$linearFill is only available in the $setWindowFields stage.

Parameters:

fillValue - the expression to use when calculating fill values

Returns:

the fill expression

Since:

2.3

Since server release

5.3

MongoDB documentation

Aggregration Expression: $linearFill

locf

public static Expression locf(Expression fillValue)

Last observation carried forward. Set values for null and missing fields in a window to the last non-null value for the field.

Parameters:

fillValue - the expression to use when calculating fill values

Returns:

the fill expression

Since:

2.3

Since server release

5.2

MongoDB documentation

Aggregration Expression: $locf

rank

public static Expression rank()

Returns the document position (known as the rank) relative to other documents in the $setWindowFields stage partition.

Returns:

the new expression

Since:

2.3

Since server release

5.0

MongoDB documentation

Aggregration Expression: $rank

shift

public static ShiftExpression shift(Expression output,
                                    long by,
                                    Expression defaultValue)

Returns the value from an expression applied to a document in a specified position relative to the current document in the $setWindowFields stage partition.

Parameters:

output - Specifies an expression to evaluate and return in the output.

by - Specifies an integer with a numeric document position relative to the current document in the output.

defaultValue - Specifies an optional default expression to evaluate if the document position is outside of the implicit $setWindowFields stage window. The implicit window contains all the documents in the partition.

Returns:

the expression

Since:

2.3

See Also:

Aggregation.setWindowFields(SetWindowFields)

Since server release

5.0

MongoDB documentation

Aggregration Expression: $shift

stdDevPop

public static Expression stdDevPop(Expression value,
                                   Expression... additional)

Returns the population standard deviation of the input values.

Parameters:

value - the value

additional - any subsequent expressions to include in the expression

Returns:

the new expression

Since:

2.3

MongoDB documentation

Aggregration Expression: $stdDevPop

stdDevSamp

public static Expression stdDevSamp(Expression value,
                                    Expression... additional)

Returns the sample standard deviation of the input values.

Parameters:

value - the value

additional - any subsequent expressions to include in the expression

Returns:

the new expression

Since:

2.3

MongoDB documentation

Aggregration Expression: $stdDevSamp