JavaScript

Question

下面有一个 CSV 文件，我想用它构建一个 javascript 对象。

我正在尝试从“类别”列中提取元素并创建层次结构对象，然后将信息放在对象最低级别的“颜色”列下。

目标：

以下是我迄今为止尝试从 CSV 中提取信息的尝试，以及确定如何从这里继续进行的操作。什么是最好最有效的？

let csv = `id, category, year, color, price \n
01, SUV > AWD > Sport > Benz, 2017, blue,  \n
02, SUV > FWD > Family > Benz, 2018, black,  \n
03, Sedan > AWD > BNW, 2017, white,  \n
04, SUV > AWD > Sport > BNW, 2012, red,  \n
05, Seden > RWD > Toyota, 2019, white, `

function extractCSV(csv){
    let object = {}
    let data = csv.split('\n')

    for(let i = 1; i < data.length; i++){
        let subData = data[i].split(',')
        for(let j = 1; j < subData.length; j++){
            let header = subData[j].split(">")

            if(header.length > 1){
                for(let k = 0; k < header.length; k++){
                    
                }
            } 
        }
    }
    return object
}

提前致谢

Answer 1

首先，两个答案中“更好”的那个。

您会发现它遵循与开始时基本相同的流程，但是，我选择将所有解析放在前面，放入一些中间对象中。这允许后面的代码专注于构建我们的树。

let csv = `id, category, year, color, price \n
01, SUV > AWD > Sport > Benz, 2017, blue,  \n
02, SUV > FWD > Family > Benz, 2018, black,  \n
03, Sedan > AWD > BNW, 2017, white,  \n
04, SUV > AWD > Sport > BNW, 2012, red,  \n
05, Sedan > RWD > Toyota, 2019, white, `;

function parseCsv(csv) {
  let object = {};

  // Parse/Sanitize all the data up front
  const rows = csv
    .split("\n")
    .filter((row, index) => index && row)
    .map((row) => {
      const columns = row.split(",");
      return {
        headers: columns[1].split(">").map((p) => p.trim()),
        color: columns[3].trim()
      };
    });

  // Then spin through the rows
  for (const row of rows) {
    let currentObj = object;

    // Then spin through the headers
    for (let hi = 0; hi < row.headers.length; ++hi) {
      const header = row.headers[hi];

      // If it is the last header, assign the color to it
      if (hi === row.headers.length - 1) {
        currentObj[header] = row.color;
        break;
      }

      // Else we need to get or set another object level
      currentObj = currentObj[header] = currentObj[header] ?? {};
    }
  }

  return object;
}

console.log(parseCsv(csv));

其次，我在这里采用了另一种方法。我发现递归解决方案有些优雅。虽然，它可能更难阅读，很可能会占用更多内存，而且速度更慢，尤其是 document/header 深度增长时。但我把它包括在内是为了好玩！

let csv = `id, category, year, color, price \n
01, SUV > AWD > Sport > Benz, 2017, blue,  \n
02, SUV > FWD > Family > Benz, 2018, black,  \n
03, Sedan > AWD > BNW, 2017, white,  \n
04, SUV > AWD > Sport > BNW, 2012, red,  \n
05, Sedan > RWD > Toyota, 2019, white, `;

const parseCsv = (csv) => {
  const result = {};

  // Parse/Sanitize all the data up front
  const rows = csv
    .split("\n")
    .filter((row, index) => index && row)
    .map((row) => {
      const columns = row.split(",");
      return {
        headers: columns[1].split('>').map(p => p.trim()),
        color: columns[3].trim()
      };
    });

  // The recursive function, takes in
  // {target} the current object in the tree we're  at
  // {headers} the remaining headers to step through
  // {color} the color to assign to the last header
  const handleRow = (target, headers, color) => {
    // Last header, so just assign the color to it
    if (headers.length === 1) {
      target[headers[0]] = color;
      return;
    }

    // Else we need to get or set another object level
    const newTarget = (target[headers[0]] = target[headers[0]] ?? {});
    // And call into the next level with it and the remaining headers
    handleRow(newTarget, headers.slice(1), color);
  };

  for (const row of rows) {
    handleRow(result, row.headers, row.color);
  }

  return result;
};

console.log(parseCsv(csv));

JavaScript - 如何从 CSV 文件构建层次结构对象

JavaScript - how to build build an hierarchy object from a CSV file

csv

binary-tree

object