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比较两个数组的内容

ramda.js javascript

Radex · 技术社区 · 7 年前

我需要比较两个数组(源/目标)对象的内容。

若目标中确实存在源中的项,我应该只添加要排除的项。

R.differenceWith() 但当目标为空时,我会遇到一个问题。

differenceWith 把海豚放在这里,否则我可以用其他功能。请给我举个例子,谢谢!

注:即使不使用ramda也可以回答。

Demo

// source
  const pathHash1 = {
    hash: "c4ca4238a0b923820dcc509a6f75849b",
    path: "./source/file1.txt"
  };
  const pathHash2 = {
    hash: "c81e728d9d4c2f636f067f89cc14862c",
    path: "./source/file2.txt"
  };
  const pathHash3 = {
    hash: "eccbc87e4b5ce2fe28308fd9f2a7baf3",
    path: "./souce/file3.txt"
  };
  // target
  const pathHash4 = {
    hash: "eccbc87e4b5ce2fe28308fd9f2a7baf3",
    path: "./target/file3.txt"
  };

// works
// const source = [pathHash1, pathHash2, pathHash3]
// const target = [pathHash4]

// does no work
const source = [pathHash1, pathHash2, pathHash3]
const target = []

// result pathHash1, pathHash2
const resultInclude = R.differenceWith((x,y)=> x.hash === y.hash, source, target)
const resultExclude= R.differenceWith((x,y)=> x.hash !== y.hash, source, target)

console.log('include',resultInclude.map(x=>x.hash))
console.log('exclude',resultExclude.map(x=>x.hash))

5 回复 | 直到 7 年前

Ori Drori 7 年前

使用 R.innerJoin 对于排除情况:

const getInclude = R.differenceWith(R.eqProps('hash'))
const getExclude = R.innerJoin(R.eqProps('hash'))

const pathHash1 = {hash: "c4ca4238a0b923820dcc509a6f75849b",path: "./source/file1.txt"},pathHash2 = {hash: "c81e728d9d4c2f636f067f89cc14862c",path: "./source/file2.txt"},pathHash3 = {hash: "eccbc87e4b5ce2fe28308fd9f2a7baf3",path: "./souce/file3.txt"},pathHash4 = {hash: "eccbc87e4b5ce2fe28308fd9f2a7baf3",path: "./target/file3.txt"}

const source1 = [pathHash1, pathHash2, pathHash3]
const target1 = [pathHash4]

const source2 = [pathHash1, pathHash2, pathHash3]
const target2 = []

const getHash = R.map(R.prop('hash'))

console.log('include1', getHash(getInclude(source1, target1)))
console.log('exclude1', getHash(getExclude(source1, target1)))

console.log('include2', getHash(getInclude(source2, target2)))
console.log('exclude2', getHash(getExclude(source2, target2)))

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.min.js"></script>

GibboK 7 年前

在香草JS中,你可以考虑使用这个版本:

  const resultInclude = pathHashListSource.filter(x => !pathHashListTarget.find(y => y.hash === x.hash));
  const resultExclude = pathHashListSource.filter(x => pathHashListTarget.find(y => y.hash === x.hash));

customcommander 7 年前

我想你可以用 difference differenceWith 对于简单对象。如果要在这两个视图中查找公共对象 source target innerJoin :

const {difference, innerJoin, equals} = R;

const a = [{x: 1}, {y: 2}, {z: 3}];
const b = [{a: 0}, {x: 1}];

console.log(
  difference(a, b)
);

console.log(
  innerJoin(equals, a, b)
);

<script src="https://cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.min.js"></script>

gaetanoM 7 年前

你从中得到的结果 R.differenceWith() 是正确的,因为这种方法的来源是:

var differenceWith = _curry3(function differenceWith(pred, first, second) {
    var out = [];
    var idx = 0;
    var firstLen = first.length;
    while (idx < firstLen) {
            if (!_includesWith(pred, first[idx], second) && 
                !_includesWith(pred, first[idx], out)) {
                out.push(first[idx]);
            }
            idx += 1;
    }
    return out;
});

正如您可以看到的,差异是使用 _包括 . 但是,当第二个数组为空时,将填充正在进行的输出数组(无重复)。

// source
const pathHash1 = {
    hash: "c4ca4238a0b923820dcc509a6f75849b",
    path: "./source/file1.txt"
};
const pathHash2 = {
    hash: "c81e728d9d4c2f636f067f89cc14862c",
    path: "./source/file2.txt"
};
const pathHash3 = {
    hash: "eccbc87e4b5ce2fe28308fd9f2a7baf3",
    path: "./souce/file3.txt"
};
// target
const pathHash4 = {
    hash: "eccbc87e4b5ce2fe28308fd9f2a7baf3",
    path: "./target/file3.txt"
};

// works
// const source = [pathHash1, pathHash2, pathHash3]
// const target = [pathHash4]

// issue
const source = [pathHash1, pathHash2, pathHash3]
const target = []

// result pathHash1, pathHash2
const resultInclude = R.differenceWith((x,y)=> x.hash === y.hash, source, target)
const resultExclude= R.differenceWith((x,y)=> x.hash !== y.hash, source, target)


console.log('include',resultInclude.map(x=>x.hash))
console.log('exclude',resultExclude.map(x=>x.hash))

<script src="https://cdn.jsdelivr.net/npm/ramda@latest/dist/ramda.min.js"></script>

Scott Christopher 7 年前

这里的另一个选择是建立本地 Set 目标哈希的定义和使用 R.partition 设置

const source = [
  {
    hash: "c4ca4238a0b923820dcc509a6f75849b",
    path: "./source/file1.txt"
  },
  {
    hash: "c81e728d9d4c2f636f067f89cc14862c",
    path: "./source/file2.txt"
  },
  {
    hash: "eccbc87e4b5ce2fe28308fd9f2a7baf3",
    path: "./souce/file3.txt"
  }
]

const target = [
  {
    hash: "eccbc87e4b5ce2fe28308fd9f2a7baf3",
    path: "./target/file3.txt"
  }
]

////

const targetHashes =
  target.reduce((hashes, next) => hashes.add(next.hash), new Set)

const [resultExclude, resultInclude] =
  R.partition(x => targetHashes.has(x.hash), source)

////

console.log("resultInclude", resultInclude)
console.log("resultExclude", resultExclude)

<script src="//cdnjs.cloudflare.com/ajax/libs/ramda/0.26.1/ramda.min.js"></script>