attempt 1: concurrently evaluate each city temperatures using goroutines

.gitignore

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+measurements.txt

README.md

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+# 1BRC

go.mod

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+module github.com/shraddhaag/1brc-go
+
+go 1.20

main.go

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+package main
+
+import (
+	"bufio"
+	"flag"
+	"fmt"
+	"log"
+	"math"
+	"os"
+	"runtime"
+	"runtime/pprof"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+)
+
+var cpuprofile = flag.String("cpuprofile", "", "write cpu profile to `file`")
+var memprofile = flag.String("memprofile", "", "write memory profile to `file`")
+
+func main() {
+
+	flag.Parse()
+	if *cpuprofile != "" {
+		f, err := os.Create("./profiles/" + *cpuprofile)
+		if err != nil {
+			log.Fatal("could not create CPU profile: ", err)
+		}
+		defer f.Close() // error handling omitted for example
+		if err := pprof.StartCPUProfile(f); err != nil {
+			log.Fatal("could not start CPU profile: ", err)
+		}
+		defer pprof.StopCPUProfile()
+	}
+
+	fmt.Println(evaluate())
+
+	if *memprofile != "" {
+		f, err := os.Create("./profiles/" + *memprofile)
+		if err != nil {
+			log.Fatal("could not create memory profile: ", err)
+		}
+		defer f.Close() // error handling omitted for example
+		runtime.GC()    // get up-to-date statistics
+		if err := pprof.WriteHeapProfile(f); err != nil {
+			log.Fatal("could not write memory profile: ", err)
+		}
+	}
+}
+
+func evaluate() string {
+	mapOfTemp, err := readFileLineByLineIntoAMap("./test_cases/measurements-1.txt")
+	if err != nil {
+		panic(err)
+	}
+
+	var result []string
+	var wg sync.WaitGroup
+	var mx sync.Mutex
+
+	updateResult := func(input string) {
+		mx.Lock()
+		defer mx.Unlock()
+
+		result = append(result, input)
+	}
+
+	for city, temps := range mapOfTemp {
+		wg.Add(1)
+		go func(city string, temps []float64) {
+			defer wg.Done()
+			sort.Float64s(temps)
+
+			var avg float64
+
+			for _, temp := range temps {
+				avg += temp
+			}
+
+			// fmt.Println(avg, len(temps))
+			avg = avg / float64(len(temps))
+			// fmt.Println(avg)
+			avg = math.Ceil(avg*10) / 10
+			// fmt.Println(avg)
+
+			updateResult(fmt.Sprintf("%s=%.1f/%.1f/%.1f", city, temps[0], avg, temps[len(temps)-1]))
+
+		}(city, temps)
+	}
+
+	wg.Wait()
+	sort.Strings(result)
+	return strings.Join(result, ", ")
+}
+
+func readFileLineByLineIntoAMap(filepath string) (map[string][]float64, error) {
+	mapOfTemp := make(map[string][]float64)
+
+	file, err := os.Open(filepath)
+	if err != nil {
+		return nil, err
+	}
+
+	scanner := bufio.NewScanner(file)
+
+	for scanner.Scan() {
+		text := scanner.Text()
+
+		index := strings.Index(text, ";")
+		city := text[:index]
+		temp := convertStringToFloat(text[index+1:])
+
+		if _, ok := mapOfTemp[city]; ok {
+			mapOfTemp[city] = append(mapOfTemp[city], temp)
+		} else {
+			mapOfTemp[city] = []float64{temp}
+		}
+	}
+
+	return mapOfTemp, nil
+}
+
+func convertStringToFloat(input string) float64 {
+	output, _ := strconv.ParseFloat(input, 64)
+	return output
+}

test_cases/measurements-1.out

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+{Kunming=19.8/19.8/19.8}

test_cases/measurements-1.txt

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+Kunming;19.8

test_cases/measurements-10.out

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+{Adelaide=15.0/15.0/15.0, Cabo San Lucas=14.9/14.9/14.9, Dodoma=22.2/22.2/22.2, Halifax=12.9/12.9/12.9, Karachi=15.4/15.4/15.4, Pittsburgh=9.7/9.7/9.7, Ségou=25.7/25.7/25.7, Tauranga=38.2/38.2/38.2, Xi'an=24.2/24.2/24.2, Zagreb=12.2/12.2/12.2}

test_cases/measurements-10.txt

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+Halifax;12.9
+Zagreb;12.2
+Cabo San Lucas;14.9
+Adelaide;15.0
+Ségou;25.7
+Pittsburgh;9.7
+Karachi;15.4
+Xi'an;24.2
+Dodoma;22.2
+Tauranga;38.2