/
filter.go
74 lines (62 loc) · 1.22 KB
/
filter.go
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package average
import (
"fmt"
"github.com/cybozu-go/goma/filters"
)
const (
defaultWindowSize = 10
)
type filter struct {
init float64
values []float64
index int
}
func (f *filter) Init() {
for i := 0; i < len(f.values); i++ {
f.values[i] = f.init
}
}
func (f *filter) Put(v float64) (avg float64) {
f.values[f.index] = v
f.index++
if f.index == len(f.values) {
f.index = 0
}
for _, t := range f.values {
avg += t
}
avg /= float64(len(f.values))
return
}
func (f *filter) String() string {
return fmt.Sprintf("filter:average(window=%d, init=%g)",
len(f.values), f.init)
}
func construct(params map[string]interface{}) (filters.Filter, error) {
var init float64
if v, ok := params["init"]; ok {
init, ok = v.(float64)
if !ok {
return nil, fmt.Errorf("init is not a float: %v", v)
}
}
var window int64 = defaultWindowSize
if v, ok := params["window"]; ok {
window, ok = v.(int64)
if !ok {
return nil, fmt.Errorf("window is not an integer: %v", v)
}
if window < 1 {
return nil, fmt.Errorf("too small window size: %d", window)
}
}
f := &filter{
init: init,
values: make([]float64, window),
}
f.Init()
return f, nil
}
func init() {
filters.Register("average", construct)
}