gem "anomaly_detection"

series = {
  Date.parse("2025-01-01") => 100,
  Date.parse("2025-01-02") => 150,
  Date.parse("2025-01-03") => 136,
  # ...
}
AnomalyDetection.detect(series, period: 7)

series = User.group_by_day(:created_at).count
AnomalyDetection.detect(series, period: 7)

series = [100, 150, 136, ...]
AnomalyDetection.detect(series, period: 7)

AnomalyDetection.detect(
  series,
  period: 7,            # number of observations in a single period
  alpha: 0.05,          # level of statistical significance
  max_anoms: 0.1,       # maximum number of anomalies as percent of data
  direction: "both",    # pos, neg, or both
  verbose: false        # show progress
)

gem "vega"

AnomalyDetection.plot(series, anomalies)