Document the argument expected for percentile-related functions

histogram.go

@@ -72,13 +72,13 @@ func (h *HistogramSnapshot) Mean() float64 { return h.sample.Mean() }
 func (h *HistogramSnapshot) Min() int64 { return h.sample.Min() }
 
 // Percentile returns an arbitrary percentile of values in the sample at the
-// time the snapshot was taken.
+// time the snapshot was taken. To get the 75th percentile, use 0.75.
 func (h *HistogramSnapshot) Percentile(p float64) float64 {
 	return h.sample.Percentile(p)
 }
 
 // Percentiles returns a slice of arbitrary percentiles of values in the sample
-// at the time the snapshot was taken.
+// at the time the snapshot was taken. To get the 75th percentile, use 0.75.
 func (h *HistogramSnapshot) Percentiles(ps []float64) []float64 {
 	return h.sample.Percentiles(ps)
 }
@@ -170,13 +170,14 @@ func (h *StandardHistogram) Mean() float64 { return h.sample.Mean() }
 // Min returns the minimum value in the sample.
 func (h *StandardHistogram) Min() int64 { return h.sample.Min() }
 
-// Percentile returns an arbitrary percentile of the values in the sample.
+// Percentile returns an arbitrary percentile of the values in the
+// sample. To get the 75th percentile, use 0.75.
 func (h *StandardHistogram) Percentile(p float64) float64 {
 	return h.sample.Percentile(p)
 }
 
 // Percentiles returns a slice of arbitrary percentiles of the values in the
-// sample.
+// sample. To get the 75th percentile, use 0.75.
 func (h *StandardHistogram) Percentiles(ps []float64) []float64 {
 	return h.sample.Percentiles(ps)
 }

sample.go

@@ -94,13 +94,14 @@ func (s *ExpDecaySample) Min() int64 {
 	return SampleMin(s.Values())
 }
 
-// Percentile returns an arbitrary percentile of values in the sample.
+// Percentile returns an arbitrary percentile of values in the
+// sample. To get the 75th percentile, use 0.75.
 func (s *ExpDecaySample) Percentile(p float64) float64 {
 	return SamplePercentile(s.Values(), p)
 }
 
 // Percentiles returns a slice of arbitrary percentiles of values in the
-// sample.
+// sample. To get the 75th percentile, use 0.75.
 func (s *ExpDecaySample) Percentiles(ps []float64) []float64 {
 	return SamplePercentiles(s.Values(), ps)
 }
@@ -268,13 +269,14 @@ func SampleMin(values []int64) int64 {
 	return min
 }
 
-// SamplePercentiles returns an arbitrary percentile of the slice of int64.
+// SamplePercentiles returns an arbitrary percentile of the slice of
+// int64. To get the 75th percentile, use 0.75.
 func SamplePercentile(values int64Slice, p float64) float64 {
 	return SamplePercentiles(values, []float64{p})[0]
 }
 
 // SamplePercentiles returns a slice of arbitrary percentiles of the slice of
-// int64.
+// int64. To get the 75th percentile, use 0.75.
 func SamplePercentiles(values int64Slice, ps []float64) []float64 {
 	scores := make([]float64, len(ps))
 	size := len(values)
@@ -327,13 +329,13 @@ func (s *SampleSnapshot) Mean() float64 { return SampleMean(s.values) }
 func (s *SampleSnapshot) Min() int64 { return SampleMin(s.values) }
 
 // Percentile returns an arbitrary percentile of values at the time the
-// snapshot was taken.
+// snapshot was taken. To get the 75th percentile, use 0.75.
 func (s *SampleSnapshot) Percentile(p float64) float64 {
 	return SamplePercentile(s.values, p)
 }
 
 // Percentiles returns a slice of arbitrary percentiles of values at the time
-// the snapshot was taken.
+// the snapshot was taken. To get the 75th percentile, use 0.75.
 func (s *SampleSnapshot) Percentiles(ps []float64) []float64 {
 	return SamplePercentiles(s.values, ps)
 }
@@ -455,15 +457,16 @@ func (s *UniformSample) Min() int64 {
 	return SampleMin(s.values)
 }
 
-// Percentile returns an arbitrary percentile of values in the sample.
+// Percentile returns an arbitrary percentile of values in the
+// sample. To get the 75th percentile, use 0.75.
 func (s *UniformSample) Percentile(p float64) float64 {
 	s.mutex.Lock()
 	defer s.mutex.Unlock()
 	return SamplePercentile(s.values, p)
 }
 
 // Percentiles returns a slice of arbitrary percentiles of values in the
-// sample.
+// sample. To get the 75th percentile, use 0.75.
 func (s *UniformSample) Percentiles(ps []float64) []float64 {
 	s.mutex.Lock()
 	defer s.mutex.Unlock()

timer.go

@@ -155,13 +155,14 @@ func (t *StandardTimer) Min() int64 {
 	return t.histogram.Min()
 }
 
-// Percentile returns an arbitrary percentile of the values in the sample.
+// Percentile returns an arbitrary percentile of the values in the
+// sample. To get the 75th percentile, use 0.75.
 func (t *StandardTimer) Percentile(p float64) float64 {
 	return t.histogram.Percentile(p)
 }
 
 // Percentiles returns a slice of arbitrary percentiles of the values in the
-// sample.
+// sample. To get the 75th percentile, use 0.75.
 func (t *StandardTimer) Percentiles(ps []float64) []float64 {
 	return t.histogram.Percentiles(ps)
 }
@@ -254,13 +255,13 @@ func (t *TimerSnapshot) Mean() float64 { return t.histogram.Mean() }
 func (t *TimerSnapshot) Min() int64 { return t.histogram.Min() }
 
 // Percentile returns an arbitrary percentile of sampled values at the time the
-// snapshot was taken.
+// snapshot was taken. To get the 75th percentile, use 0.75.
 func (t *TimerSnapshot) Percentile(p float64) float64 {
 	return t.histogram.Percentile(p)
 }
 
 // Percentiles returns a slice of arbitrary percentiles of sampled values at
-// the time the snapshot was taken.
+// the time the snapshot was taken. To get the 75th percentile, use 0.75.
 func (t *TimerSnapshot) Percentiles(ps []float64) []float64 {
 	return t.histogram.Percentiles(ps)
 }