[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, )), 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, ));
/*
* 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"
]
* */
[Ramda] Get a List of Unique Values From Nested Arrays with Ramda (flatMap --> Chain)的更多相关文章
- SharePoint 2013 Content Deployment 报错 These columns don't currently have unique values
错误描述: These columns don't currently have unique values. Content deployment job 'job name' failed.The ...
- Choose unique values for the 'webAppRootKey' context-param in your web.xml files!
在Tomcat的server.xml中配置两个context,出现其中一个不能正常启动,交换配置顺序,另一个又不能正常启动,即始终只有第二个配置能启动的情况.如果单独部署,都没有问题.报错大致内容如下 ...
- find unique values in an array
Problem: given an array that contains duplicates (except one value), find the one value that does no ...
- tomcat下部署了多个项目启动报错java web error:Choose unique values for the 'webAppRootKey' context-param in your web.xml files
应该是tomcat下部署了多个项目且都使用log4j. <!--如果不定义webAppRootKey参数,那么webAppRootKey就是缺省的"webapp.root". ...
- Choose unique values for the 'webAppRootKey' context-param in your web.xml files! 错误的解决
大意是Log4jConfigListener在获取webapp.root值时,被后一context的值替换掉了,所以要在各个项目的web.xml中配置不同的webAppRootKey值,随即在其中一个 ...
- [Ramda] Convert a QueryString to an Object using Function Composition in Ramda
In this lesson we'll use a handful of Ramda's utility functions to take a queryString full of name/v ...
- Linq101-Set
using System; using System.Collections.Generic; using System.Linq; namespace Linq101 { class Set { / ...
- coffeescript 1.8.0 documents
CoffeeScript is a little language that compiles into JavaScript. Underneath that awkward Java-esque ...
- how to use coffee script
TABLE OF CONTENTS TRY COFFEESCRIPT ANNOTATED SOURCE CoffeeScript is a little language that compiles ...
随机推荐
- percona-toolkit的安装及简单介绍
MySQL数据库是轻量级.开源数据库的佼佼者.其功能和管理,健壮性与Oracle相比还是有相当的差距.因此有非常多功能强大第三方的衍生产品,如percona-toolkit,XtraBackup等等. ...
- 【河南省多校脸萌第六场 A】巴什博弈?
[链接]http://acm.nyist.me/JudgeOnline/problem.php?cid=1013&pid=5 [题意] 在这里写题意 [题解] 0..a-1 YES a..a+ ...
- 忍者无敌-实例解说Cocos2d-x瓦片地图
实例比較简单,如图所看到的,地图上有一个忍者精灵,玩家点击他周围的上.下.左.右,他能够向这个方向行走. 当他遇到障碍物后是无法穿越的,障碍物是除了草地以为部分,包含了:树.山.河流等. 忍者实例地图 ...
- Tomcat源代码阅读#1:classloader初始化
Bootstrap 通过Tomcat的启动脚本能够看到启动的入口是在Bootstrap,来看下Bootstrap的main方法, /** * Main method and entry point w ...
- vue使用(二)
本节目标: 1.数据路径的三种方式 2.{{}}和v-html的区别 1.绑定图片的路径 方法一:直接写路径 <img src="http://p ...
- Spring拦截器和Servlet过滤器区别
http://blog.csdn.net/chenleixing/article/details/44573495
- 51NOD——N 1107 斜率小于0的连线数量
https://www.51nod.com/onlineJudge/questionCode.html#!problemId=1107 基准时间限制:1 秒 空间限制:131072 KB 分值: 40 ...
- WGS84与WGS84 Web Mercator
1. WGS84与WGS84 Web Mercator 1.1 关于WGS1984投影坐标系 UTM (Universal Transverse Mercator)坐标系是由美国军方在1947提出的. ...
- Maven 使用Eclipse构建Maven的SpringMVC项目
首先Eclipse需要安装Maven的插件,地址:http://m2eclipse.sonatype.org/sites/m2e. 用MyEclipse安装Maven插件,建出的Maven项目有些问题 ...
- 8.4 Android灯光系统_源码分析_电池灯
电池灯的Java代码在batteryservice.java中 电池的状态电量等信息由驱动获得,但驱动不会主动做这些事情,因此肯定有个App调用驱动程序读取电池信息,称这个App为A应用. 还有个Ap ...