go-chart/last_value_annotation.go

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package chart
import "fmt"
// LastValueAnnotation returns an annotation series of just the last value of a value provider.
func LastValueAnnotation(innerSeries ValuesProvider, vfs ...ValueFormatter) AnnotationSeries {
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var vf ValueFormatter
if len(vfs) > 0 {
vf = vfs[0]
} else if typed, isTyped := innerSeries.(ValueFormatterProvider); isTyped {
_, vf = typed.GetValueFormatters()
} else {
vf = FloatValueFormatter
}
var lastValue Value2
if typed, isTyped := innerSeries.(LastValuesProvider); isTyped {
lastValue.XValue, lastValue.YValue = typed.GetLastValues()
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lastValue.Label = vf(lastValue.YValue)
} else {
lastValue.XValue, lastValue.YValue = innerSeries.GetValues(innerSeries.Len() - 1)
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lastValue.Label = vf(lastValue.YValue)
}
var seriesName string
var seriesStyle Style
if typed, isTyped := innerSeries.(Series); isTyped {
seriesName = fmt.Sprintf("%s - Last Value", typed.GetName())
seriesStyle = typed.GetStyle()
}
return AnnotationSeries{
Name: seriesName,
Style: seriesStyle,
Annotations: []Value2{lastValue},
}
}