获取分组数组(JavaScript)的2个索引之间的差异

Question

我从加密交易的CSV文件中提取了数据，并使用Token列对结果进行了分组。以下是分组数组看起来像的样子

**[
ETH:[
[ 1571967200, 'DEPOSIT', 'ETH', 0.68364 ],    
[ 1571967189, 'WITHDRAWAL', 'ETH', 0.493839 ],
[ 1571967110, 'DEPOSIT', 'ETH', 0.347595 ],   
[ 1571966982, 'WITHDRAWAL', 'ETH', 0.266166 ],
[ 1571966641, 'DEPOSIT', 'ETH', 0.899781 ],   
[ 1571966421, 'DEPOSIT', 'ETH', 0.218207 ],   
[ 1571966410, 'DEPOSIT', 'ETH', 0.205472 ],   
[ 1571966250, 'WITHDRAWAL', 'ETH', 0.761543 ],
[ 1571966124, 'DEPOSIT', 'ETH', 0.66315 ],    
[ 1571965892, 'DEPOSIT', 'ETH', 0.554933 ]    
],
BTC: [
[ 1571966685, 'DEPOSIT', 'BTC', 0.658794 ],
[ 1571966568, 'DEPOSIT', 'BTC', 0.630386 ],
[ 1571966566, 'DEPOSIT', 'BTC', 0.985879 ],
[ 1571966499, 'DEPOSIT', 'BTC', 0.162165 ],
[ 1571966329, 'WITHDRAWAL', 'BTC', 0.063663 ],
[ 1571966194, 'DEPOSIT', 'BTC', 0.858688 ],
[ 1571966049, 'DEPOSIT', 'BTC', 0.696682 ],
[ 1571966026, 'DEPOSIT', 'BTC', 0.747093 ],
[ 1571965990, 'WITHDRAWAL', 'BTC', 0.987358 ]
]
]**

这是我用来分组的代码

inputStream.pipe(new CsvReadableStream({ parseNumbers: true, parseBooleans: true, trim: true }))
.on('data', (row)=> {
csvData.push(row);
})
.on('end', function () {
groupedResult = csvData.reduce((acc, curr) => {

if(!acc[curr[2]]){
acc[curr[2]] = [];
}
acc[curr[2]].push(curr);
return acc;
},[]);
});

我正试着把所有的存款加在一起，并对每组的提款进行细分。下面是我用来将withdrwals和存款组合在一起的代码，但不幸的是，它不起作用。我可能做错了什么，或者我如何添加所有存款并减去每个代币的withdrwals？

for(groupName in groupedResult){
groupedResult[groupName].reduce((acc, curr)=>{
acc[curr[1]] = curr[1];

},[])
}

这是我得到的错误

acc[curr[1]] = curr[1];
^
TypeError: Cannot set property 'WITHDRAWAL' of undefined
at E:Command Linebinindex.js:46:34
at Array.reduce (<anonymous>)

这是我想要得到的结果

[
ETH:[
[
Balance['Value here'] 
],      
],
BTC: [
[
Balance['value here'] 
],
]
]

Answer 1

；减速器"；Array#reduce(reducer, initValue, ...)的回调必须返回累加器值(return acc;)以便在下一轮中使用
这是因为您可能必须处理不保持一致引用的基元值，例如，在您想要对数字列表求和的情况下：[1, 2, 3, 4].reduce((number,acc) => {return number+acc;}, 0)

const groupedResult = {
ETH:[
[ 1571967200, 'DEPOSIT', 'ETH', 0.68364 ],    
[ 1571967189, 'WITHDRAWAL', 'ETH', 0.493839 ],
[ 1571967110, 'DEPOSIT', 'ETH', 0.347595 ],   
[ 1571966982, 'WITHDRAWAL', 'ETH', 0.266166 ],
[ 1571966641, 'DEPOSIT', 'ETH', 0.899781 ],   
[ 1571966421, 'DEPOSIT', 'ETH', 0.218207 ],   
[ 1571966410, 'DEPOSIT', 'ETH', 0.205472 ],   
[ 1571966250, 'WITHDRAWAL', 'ETH', 0.761543 ],
[ 1571966124, 'DEPOSIT', 'ETH', 0.66315 ],    
[ 1571965892, 'DEPOSIT', 'ETH', 0.554933 ]    
],
BTC: [
[ 1571966685, 'DEPOSIT', 'BTC', 0.658794 ],
[ 1571966568, 'DEPOSIT', 'BTC', 0.630386 ],
[ 1571966566, 'DEPOSIT', 'BTC', 0.985879 ],
[ 1571966499, 'DEPOSIT', 'BTC', 0.162165 ],
[ 1571966329, 'WITHDRAWAL', 'BTC', 0.063663 ],
[ 1571966194, 'DEPOSIT', 'BTC', 0.858688 ],
[ 1571966049, 'DEPOSIT', 'BTC', 0.696682 ],
[ 1571966026, 'DEPOSIT', 'BTC', 0.747093 ],
[ 1571965990, 'WITHDRAWAL', 'BTC', 0.987358 ]
]
};
const groupedBalance = {};
for(groupName in groupedResult) {
const accumulated = groupedResult[groupName].reduce((acc, curr)=>{
acc[curr[1]] += curr[3];
return acc; // ← return the accumulator to use for the next round
}, {DEPOSIT: 0, WITHDRAWAL: 0});
console.log(groupName, accumulated);
groupedBalance[groupName] = {
Balance: accumulated['DEPOSIT'] - accumulated['WITHDRAWAL']
};
}
console.log('FINAL RESULTS:', groupedBalance);