使用Golang读取csv，对列进行重新排序，然后使用并发将结果写入新的csv

问题描述

这是我的出发点.

这是一个Golang脚本，用于读取具有3列的csv，重新排序各列并将结果写入新的csv文件中.

It is a Golang script to read in a csv with 3 columns, re-order the columns and write the result to a new csv file.

package main

import (
   "fmt"
   "encoding/csv"
   "io"
   "os"
   "math/rand"
   "time"
)

func main(){
  start_time := time.Now()

  // Loading csv file
  rFile, err := os.Open("data/small.csv") //3 columns
  if err != nil {
    fmt.Println("Error:", err)
    return
   }
  defer rFile.Close()

  // Creating csv reader
  reader := csv.NewReader(rFile)

  lines, err := reader.ReadAll()
  if err == io.EOF {
      fmt.Println("Error:", err)
      return
  }

  // Creating csv writer
  wFile, err := os.Create("data/result.csv")
  if err != nil {
      fmt.Println("Error:",err)
      return
  }
  defer wFile.Close()
  writer := csv.NewWriter(wFile)

  // Read data, randomize columns and write new lines to results.csv
  rand.Seed(int64(time.Now().Nanosecond()))
  var col_index []int
  for i,line :=range lines{
      if i == 0 {
        //randomize column index based on the number of columns recorded in the 1st line
        col_index = rand.Perm(len(line))
    }
    writer.Write([]string{line[col_index[0]], line[col_index[1]], line[col_index[2]]}) //3 columns
    writer.Flush()
}

//print report
fmt.Println("No. of lines: ",len(lines))
fmt.Println("Time taken: ", time.Since(start_time))

}

问题:

1. 我的代码是Golang惯用的吗?

1. Is my code idiomatic for Golang?

如何在此代码中添加并发?

How can I add concurrency to this code?

推荐答案

 Read() ReadAll()

Read()ReadAll()

for line, err := reader.Read(); err == nil; line, err = reader.Read(){
    if err = writer.Write([]string{line[col_index[0]], line[col_index[1]], line[col_index[2]]}); err != nil {
            fmt.Println("Error:", err)
            break
    }
    writer.Flush()
}

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