zoukankan      html  css  js  c++  java
  • [Ramda] Get a List of Unique Values From Nested Arrays with Ramda (flatMap --> Chain)

    In this lesson, we'll grab arrays of values from other arrays, resulting in a nested array. From there, we'll look at multiple ways to flatten the array structure using composition with map and unnest and then refactoring to use chain, AKA flatMap. Finally, we'll add Ramda's uniq function to remove duplicate values.

    const R = require('ramda');
    
    const {map, chain, prop, pluck, compose, uniq, tap, curry} = R;
    
    const product = {
        name: "Sample Data",
        sizes: [
            {
                name: "L",
                colors: [
                    {
                        name: "Red"
                    },
                    {
                        name: "Blue"
                    }
                ]
            },
            {
                name: "M",
                colors: [
                    {
                        name: "Green"
                    },
                    {
                        name: "Yellow"
                    }
                ]
            },
            {
                name: "S",
                colors: [
                    {
                        name: "Orange"
                    },
                    {
                        name: "Purple"
                    },
                    {
                        name: "Blue"
                    }
                ]
            }
        ]
    };
    
    const log = curry((desc, x) => R.tap(() => console.log(desc, JSON.stringify(x, null, 2)), x));
    
    // Target: to get unique array of color from product object
    
    const sizes = prop('sizes');
    const getColors = chain(prop('colors')); // flatMap, get colors props from array of objects
    const getColorNames = pluck('name'); // get name prop from array of objects
    const res = compose(
        uniq,
        log("after name"),
        getColorNames,
        log("after colors"),
        getColors,
        log("after sizes"),
        sizes
    )(product);
    
    console.log(JSON.stringify(res, null, 2));
    /*
    * after sizes [
      {
        "name": "L",
        "colors": [
          {
            "name": "Red"
          },
          {
            "name": "Blue"
          }
        ]
      },
      {
        "name": "M",
        "colors": [
          {
            "name": "Green"
          },
          {
            "name": "Yellow"
          }
        ]
      },
      {
        "name": "S",
        "colors": [
          {
            "name": "Orange"
          },
          {
            "name": "Purple"
          },
          {
            "name": "Blue"
          }
        ]
      }
    ]
    after colors [
      {
        "name": "Red"
      },
      {
        "name": "Blue"
      },
      {
        "name": "Green"
      },
      {
        "name": "Yellow"
      },
      {
        "name": "Orange"
      },
      {
        "name": "Purple"
      },
      {
        "name": "Blue"
      }
    ]
    after name [
      "Red",
      "Blue",
      "Green",
      "Yellow",
      "Orange",
      "Purple",
      "Blue"
    ]
    [
      "Red",
      "Blue",
      "Green",
      "Yellow",
      "Orange",
      "Purple"
    ]
    * */
  • 相关阅读:
    Convolution_model_Application_v1a
    MBSE基于模型的系统工程
    Convolution_model_Step_by_Step_v2a
    深度学习精炼图笔记总结
    TensorFlow_Tutorial_v3b——improving NN performance测验
    maven之安装jar包之本地仓库
    linux之rpm管理
    linux之防火墙
    linux之ntp服务
    linux之chkconfig
  • 原文地址:https://www.cnblogs.com/Answer1215/p/6480706.html
Copyright © 2011-2022 走看看