Custom Find based on Identified Index

find.go

package main

import (
	"encoding/csv"
	"fmt"
	"io"
	"log"
	"os"
	"sort"
)

func main() {
	programmap("ace.csv", "AK1305", 1, 0)

}

func programmap(file string, prog string, course int, student int) {
	var header []string
	cxmap := make(map[string][]string) //map of student
	var stds []string
	cxfinal := [][]string{}
	count := 0

	csvFile, err := os.Open(file)
	if err != nil {
		log.Fatal(err)
	}

	f := csv.NewReader(csvFile)

	for {

		if count > 50000 {
			break
		}
		record, err := f.Read()

		if err == io.EOF {
			break
		}

		count++

		if err != nil {
			log.Fatal(err)
		}

		if header == nil {
			header = record
			continue
		}

		cxmap[record[student]] = append(cxmap[record[student]], record[course])

		if record[course] == prog {
			stds = append(stds, record[student])
			fmt.Println(cxmap[record[student]])

		}
	}

	sort.Strings(stds)

	for _, v := range stds {
		temp := make([]string, 0)
		temp = append(temp, v)
		sort.Strings(cxmap[v])
		temp = append(temp, cxmap[v]...)
		cxfinal = append(cxfinal, [][]string{temp}...)

	}

	writecsv(cxfinal)
}

func writecsv(rows [][]string) {

	csvfile, err := os.Create("test.csv")

	if err != nil {
		log.Fatalf("failed creating file: %s", err)
	}

	csvwriter := csv.NewWriter(csvfile)

	for _, row := range rows {
		_ = csvwriter.Write(row)
	}

	csvwriter.Flush()

	csvfile.Close()

}