helper.go

package helper

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"

	"golang.org/x/exp/slices"
)

func GetContinue() bool {
	var cont string
	for {
		
		fmt.Println("Do you want to continue (yes/no)? ")
		fmt.Scanln(&cont)

		if strings.ToLower(cont) == "no" {
			return false
		} else if strings.ToLower(cont) == "yes" {
			return true
		}
	}

}

// not clear that this gets the User from stdin, maybe call it something like "ReadInUser"
// the usercap you pass in is not actually the cap, since you use "userCap-1" everywhere
// expect that value instead and adjust the callers
func GetUser(userCap int) int {
	var user string

	for {
		fmt.Printf("\nEnter an integer in the range 0 to %d:", userCap-1)
		fmt.Scanln(&user)

		userNum, err := strconv.Atoi(user)
		if err != nil {
			fmt.Println("Error: input must be an int between 0 and 9")
			continue
		}

		if userNum > userCap-1 || userNum < 0 {
			fmt.Println("Error: input must be an int between 0 and 9")
			continue
		}
		return userNum

	}

}

// this can probably be done in the one place it's called in
// can be abstracted into a util if needed more often (>3 times)
func CreateMatrix(rows int) [][]int {
	var matrix [][]int

	for i := 0; i < rows; i++ {
		matrix = append(matrix, []int{})
	}

	return matrix
}

func OpenFile() *os.File {

	for {
		var fileName string
		fmt.Println("Enter a filename: ")
		fmt.Scanln(&fileName)

		fp, err := os.Open(fileName)

		if err != nil {
			fmt.Println("\nError in filename.")
		} else {
			return fp
		}
	}
	// remove for production 🤓
	//for testing
	// fp, _ := os.Open("small_network_data.txt")
	//return fp
}

// include in name that a network is returned
func ReadFile(fp *os.File) [][]int {
	scanner := bufio.NewScanner(fp)

	//Get header (total number of users) and convert to int
	scanner.Scan()
	userLine := scanner.Text()
	numUsers, _ := strconv.Atoi(userLine)

	var network [][]int = CreateMatrix(numUsers)

	for scanner.Scan() {
		friends := strings.Fields(scanner.Text())

		// handle error
		f1, _ := strconv.Atoi(friends[0])
		f2, _ := strconv.Atoi(friends[1])

		network[f1] = append(network[f1], f2)
		network[f2] = append(network[f2], f1)
	}

	return network
}

// function should hide complexity, name could be "CalculateSimilarityScore"
// parameters could be "user1" and "user2"
func NumInCommonBetweenLists(user []int, other []int) int {

	var inCommon int = 0

	// use range to loop over user instead, much simpler 🤓
	for i := 0; i < len(user); i++ {
		if slices.Contains(other, user[i]) {
			inCommon += 1
		}
	}

	return inCommon
}

func CalcSimilarityScores(network [][]int) [][]int {
	var simScores [][]int = CreateMatrix(len(network))

	// can use "for range"
	for i := 0; i < len(network); i++ {
		for j := 0; j < len(network); j++ {

			var inCommon int = NumInCommonBetweenLists(network[i], network[j])
			simScores[i] = append(simScores[i], inCommon)

		}
	}

	return simScores
}

// pass in userFriends instead of network, matrix is implied by the type, can be more descriptive than "simMatrix"
func Recommend(user int, network [][]int, simMatrix [][]int) int {
	var suggestedUser int
	var mostCompatible int = 0

	uFriends := network[user]
	// uMatrix very non-descriptive
	uMatrix := simMatrix[user]

	for i := 0; i < len(simMatrix); i++ {
		if i == user {
			continue
		}
		if slices.Contains(uFriends, i) {
			continue
		}

		currentCompatible := uMatrix[i]

		if currentCompatible > mostCompatible {
			suggestedUser = i
			mostCompatible = currentCompatible
		}
	}

	return suggestedUser
}

main.go

package main

import (
	"fmt"
	"p5/helper"
)

func main() {
	// confusing empty line, did you format with gofmt?
	fmt.Println("Facebook friend recommendation.")

	// why is this not done inside of helper.ReadFile()
	// We don't need access to the file here
	fp := helper.OpenFile()
	defer fp.Close()
	var network [][]int = helper.ReadFile(fp)

	for {

		var user int = helper.GetUser(len(network))

		// clear that it's a matrix from the return type
		// maybe call it something more descriptive like "similiarityScores"
		simMatrix := helper.CalcSimilarityScores(network)
		suggestedUser := helper.Recommend(user, network, simMatrix)

		fmt.Printf("\nThe suggested friend for %d is %d\n", user, suggestedUser)

		if !helper.GetContinue() {
			break
		}
	}

}