dsp highpass filter example

main.go

package main

import (
	"fmt"
	"log"
	"math"
	"net/http"

	"github.com/eripe970/go-dsp-utils"
	"github.com/go-echarts/go-echarts/v2/charts"
	"github.com/go-echarts/go-echarts/v2/components"
	"github.com/go-echarts/go-echarts/v2/opts"
	"github.com/go-echarts/go-echarts/v2/types"
	"github.com/jfcg/butter"
)

func main() {
	http.HandleFunc("/", handler)
	log.Fatal(http.ListenAndServe(":4000", nil))
}

func handler(w http.ResponseWriter, r *http.Request) {

	if r.URL.Path != "/" {
		return
	}

	fmt.Println("---")
	// A-1. Read the original signal---------------------------
	signal1, err := dsp.ReadSignalFile("./tidal_sample_part.txt", 0.0166666)
	if err != nil {
		fmt.Println("error reading signal file:", err)
	}
	fmt.Println("source:", signal1)
	plot_orig := plotSignal(signal1, opts.Title{
		Title:    "original signal",
		Subtitle: signal1.String(),
	})

	normalized, _ := signal1.Normalize()

	// A-4. DO High pass filter-------------------------------
	filtered, err := signal1.HighPassFilter(0.0005)
	if err != nil {
		fmt.Println("filtering error:", err)
	}
	fmt.Println("filtered:", filtered.Signal[0:10])
	plot_filtered := plotSignal(filtered, opts.Title{
		Title:    "filtered signal with 86400 sample",
		Subtitle: filtered.String(),
	})

	normalizedfiltered, err := normalized.HighPassFilter(0.0005)
	if err != nil {
		fmt.Println("filtering error:", err)
	}
	fmt.Println("filtered:", normalizedfiltered.Signal[0:10])
	plot_normalized_filtered := plotSignal(normalizedfiltered, opts.Title{
		Title:    "normalized-filtered signal with 86400 sample",
		Subtitle: filtered.String(),
	})

	bFiltered := make([]float64, signal1.Length())
	butterHPF := butter.NewHighPass1(2 * math.Pi * 0.0005 / 0.0166666)

	butterHPF.NextS(signal1.Signal, bFiltered)
	fmt.Println("bFiltered:", bFiltered[0:10])
	filtered.Signal = bFiltered // fake, lazy to implement another plotter
	plot_butter := plotSignal(filtered, opts.Title{
		Title:    "butter version, filtered signal with 86400 sample",
		Subtitle: filtered.String(),
	})

	butterHPF2 := butter.NewHighPass1(2 * math.Pi * 0.0005 / 0.0166666)

	butterHPF2.NextS(normalized.Signal, bFiltered)
	fmt.Println("bFiltered:", bFiltered[0:10])
	filtered.Signal = bFiltered // fake, lazy to implement another plotter
	plot_butter_normalized := plotSignal(filtered, opts.Title{
		Title:    "butter version, normalized-filtered signal with 86400 sample",
		Subtitle: filtered.String(),
	})

	page := components.NewPage()
	page.AddCharts(
		plot_orig,
		plot_filtered,
		plot_normalized_filtered,
		plot_butter,
		plot_butter_normalized,
	)
	page.Render(w)
}

func plotSignal(signal *dsp.Signal, title opts.Title) *charts.Line {
	x := make([]string, 0)
	y := make([]opts.LineData, 0)
	for i := 0; i < signal.Length(); i++ {
		x = append(x, fmt.Sprintf("%.1f", float64(i)/signal.SampleRate))
		y = append(y, opts.LineData{Value: signal.Signal[i], Symbol: "none"})
	}
	line := charts.NewLine()
	line.SetGlobalOptions(
		charts.WithInitializationOpts(opts.Initialization{Theme: types.ThemeWonderland}),
		charts.WithYAxisOpts(opts.YAxis{Max: signal.Max(), Min: signal.Min(), SplitNumber: 10}),
		charts.WithXAxisOpts(opts.XAxis{SplitNumber: 10}),
		charts.WithTitleOpts(title))
	line.SetXAxis(x).AddSeries("data", y).SetSeriesOptions(
		charts.WithLineChartOpts(opts.LineChart{
			Smooth: true,
		}),
	)
	return line
}