Implemented the Biased Reservoir Sampling approach [1] as a package in Go. A common interface may simplify to integrate further sampling techniques.

For compiling/running the examples the following tools are required:

• Go - https://golang.org
• gnuplot - http://www.gnuplot.info/, that's only for the example

• Install Homebrew https://brew.sh/
• brew install go gnuplot

All samplers implement the following simple interface:

type Sampler interface {
    // Add adds one or multiple samples to the Sampler.
    // Returns a set of dropped samples in this step.
    Add(samples []Sample) []Sample

    // Data returns a slice of the current samples within the Sampler.
    Data() []Sample

    // Reset resets the state of the sampler
    Reset()
}

Get the library

go get -u github.com/andremueller/goreservoir

Use the library by including the algorithm in your code

import "github.com/andremueller/goreservoir/pkg/reservoir"

The following algorithms are implemented:

• Sliding implements a basic sliding window <github.com/andremueller/goreservoir/pkg/window>.
• The DynamicSampler implements the Alg. 3.1 of [1] - the biased reservoir sampling <github.com/andremueller/goreservoir/pkg/reservoir>.
• The EnsembleSampler distributes the same data points to multiple samplers - so you can do some sort of bootstrapping.
• The ChainSampler can be used to stack the output (dropped points) of one sampler into the next one.

A simple example of the ChainSampler used together with a DynamicSampler can be found in <github.com/andremueller/goreservoir/cmd/reservoir/main.go> Output of the example is the lingering time (in steps) how long a data point is in the reservoir.

• Do some evaluation on open data sets such as https://ti.arc.nasa.gov/tech/dash/groups/pcoe/prognostic-data-repository/
• Provide more examples.

• [1] Aggarwal, C. C. On biased reservoir sampling in the presence of stream evolution. in Proceedings of the 32nd international conference on Very large data bases 607–618 (ACM Press, 2006).