44 lines
1.5 KiB
Go
44 lines
1.5 KiB
Go
// Copyright 2014 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package sampling
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import "testing"
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func TestChainSampler(t *testing.T) {
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numSamples := 10
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windowSize := 10 * numSamples
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numObservations := 10 * windowSize
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numSampleRounds := 10 * numObservations
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s := NewChainSampler(numSamples, windowSize)
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hist := make(map[int]int, numSamples)
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for i := 0; i < numSampleRounds; i++ {
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sampleStream(hist, numObservations, s)
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}
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ratio := histStddev(hist) / histMean(hist)
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if ratio > 1.05 {
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// XXX(dengnan): better sampler?
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t.Errorf("std dev: %v; mean: %v. Either we have a really bad PRNG, or a bad implementation", histStddev(hist), histMean(hist))
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}
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if len(hist) > windowSize {
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t.Errorf("sampled %v data. larger than window size %v", len(hist), windowSize)
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}
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for seqNum, freq := range hist {
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if seqNum < numObservations-windowSize && freq > 0 {
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t.Errorf("observation with seqnum %v is sampled %v times", seqNum, freq)
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}
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}
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}
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