In MongoDB, the $setDifference aggregation pipeline operator accepts two sets and performs a relative complement of the second set relative to the first. It returns an array containing the elements that only exist in the first set.
$setDifference accepts two arguments, both of which can be any valid expression as long as they each resolve to an array. $setDifference treats the arrays as sets.
In MongoDB, the $sampleRate aggregation pipeline stage matches a random selection of input documents.
The number of documents selected approximates the sample rate expressed as a percentage of the total number of documents.
The $sampleRate operator was introduced in MongoDB 4.4.2.
In MongoDB, the $reverseArray aggregation pipeline operator reverses the order of items in an array.
It accepts an array expression as an argument and returns an array with the elements in reverse order.
In MongoDB, the $range aggregation pipeline operator returns a generated sequence of numbers in an array.
This sequence of numbers is based on the input values you provide.
In MongoDB, the $round aggregation pipeline operator rounds a number to a whole integer or to a specified decimal place.
You have the option of specifying how many decimal places for which to round the number. To do this, pass a second argument. The first argument is the number to round, and the second (optional) argument is the number of decimal places to round it to.
In MongoDB, the $sample aggregation pipeline stage randomly selects the specified number of documents from its input.
In MongoDB, the $rand aggregation pipeline operator returns a random float between 0 and 1.
The floating point value has up to 17 digits after the decimal point. Any trailing zeros are dropped, so the number of digits may vary.
The $rand operator was introduced in MongoDB 4.4.2.
In MongoDB, the $nin query operator selects the documents where the field’s value is not in the specified array or where the field doesn’t exist.
In MongoDB, the $ne aggregation pipeline operator compares two values and returns either true or false, depending on whether the two values are not equivalent.
In MongoDB, the $in aggregation pipeline operator returns a boolean indicating whether a specified value is in the array.
The $in aggregation pipeline operator is not to be confused with the $in query operator, which selects the documents where the value of a field equals any value in the specified array.