serie

type Interfacer interface {
	Interface() interface{}
}

type Iterator interface {
	Next() bool
	Current() interface{}
	Reset()
}

type NullBool struct {
	Bool  bool
	Valid bool
}

type NullFloat32 struct {
	Float32 float32
	Valid   bool
}

type NullFloat64 struct {
	Float64 float64
	Valid   bool
}

type NullInt struct {
	Int   int
	Valid bool
}

type NullInt32 struct {
	Int32 int32
	Valid bool
}

type NullInt64 struct {
	Int64 int64
	Valid bool
}

type NullString struct {
	String string
	Valid  bool
}

type NullTime struct {
	Time  time.Time
	Valid bool
}

type RawValue struct {
	Value interface{}
	Valid bool
}

type Serie interface {
	Type() reflect.Type
	Slice() interface{}     // Underlying slice
	Get(at int) interface{} // T[i]. If T is an interfacer, returns Interfaced value
	All() []interface{}

	// Iterate
	Iterator() Iterator

	// Mutate
	Append(v ...interface{})
	Prepend(v ...interface{}) error
	Insert(at int, v ...interface{}) error
	Set(at int, v interface{}) error
	Delete(at int) error
	Grow(size int) error
	Shrink(size int) error
	Concat(serie ...Serie) error
	Clear()

	// Select
	Head(size int) Serie
	Tail(size int) Serie
	Subset(at, size int) Serie
	Distinct() Serie
	Pick(at ...int) Serie
	Where(predicate func(interface{}) bool) Serie
	NonNils() Serie

	// Copy
	EmptyCopy() Serie
	Copy() Serie

	// Sort
	sort.Interface
	Compare(i, j int) int
	SortAsc()
	SortDesc()

	// Statistics
	Avg(opt ...StatOption) float64
	Count(opt ...StatOption) int64
	CountDistinct(opt ...StatOption) int64
	Cusum(opt ...StatOption) []float64
	Max(opt ...StatOption) float64
	Min(opt ...StatOption) float64
	Median(opt ...StatOption) float64
	Stddev(opt ...StatOption) float64
	Sum(opt ...StatOption) float64
	Variance(opt ...StatOption) float64
}

type StatOption func(opts *StatOptions)

type StatOptions struct {
	Missing *float64 // replaces missing values with a value
}