RosettaCodeData/Task/CSV-data-manipulation/Go/csv-data-manipulation.go

package main

import (
   "encoding/csv"
   "log"
   "os"
   "strconv"
)

func main() {
   rows := readSample()
   appendSum(rows)
   writeChanges(rows)
}

func readSample() [][]string {
   f, err := os.Open("sample.csv")
   if err != nil {
      log.Fatal(err)
   }
   rows, err := csv.NewReader(f).ReadAll()
   f.Close()
   if err != nil {
      log.Fatal(err)
   }
   return rows
}

func appendSum(rows [][]string) {
   rows[0] = append(rows[0], "SUM")
   for i := 1; i < len(rows); i++ {
      rows[i] = append(rows[i], sum(rows[i]))
   }
}

func sum(row []string) string {
   sum := 0
   for _, s := range row {
      x, err := strconv.Atoi(s)
      if err != nil {
         return "NA"
      }
      sum += x
   }
   return strconv.Itoa(sum)
}

func writeChanges(rows [][]string) {
   f, err := os.Create("output.csv")
   if err != nil {
      log.Fatal(err)
   }
   err = csv.NewWriter(f).WriteAll(rows)
   f.Close()
   if err != nil {
      log.Fatal(err)
   }
}