There is an array of objects
[
{a:1,val:[11,12]},
{a:9,val:[21,22]},
{a:7,val:[31,32]},
{a:8,val:[41,42]}
]
I am trying to convert it into:
[ [{a:1,val:11},{a:9,val:21},{a:7,val:31},{a:8,val:41}] ,
[{a:1,val:12},{a:9,val:22},{a:7,val:32},{a:8,val:42}]
]
How can I use underscore.js chain/map/pluck etc... function to get the flatten result in specified format in the cleanest way?
You could use Array#forEach and build the nested parts upon.
var data = [{ a: 1, val: [11, 12] }, { a: 9, val: [21, 22] }, { a: 7, val: [31, 32] }, { a: 8, val: [41, 42] }],
result = [];
data.forEach(function (a, i) {
a.val.forEach(function (b, j) {
result[j] = result[j] || [];
result[j][i] = { a: a.a, val: b };
});
});
console.log(result);You can use array's reduce like this
var data = [
{a:1,val:[11,12]},
{a:9,val:[21,22]},
{a:7,val:[31,32]},
{a:8,val:[41,42]}
]
var result = data.reduce((res, next) => {
res[0].push({a: next.a, val: next.val[0]});
res[1].push({a: next.a, val: next.val[1]});
return res;
}, [[], []])
console.dir(result)I have done as you have requested but used plain ES6 instead of underscore.
var restructure = (x)=>
[x.map(({a,val})=>({a,val:val[0]})),x.map(({a,val})=>({a,val:val[1]}))]
var result = restructure([
{a:1,val:[11,12]},
{a:9,val:[21,22]},
{a:7,val:[31,32]},
{a:8,val:[41,42]}
])
//[[{"a":1,"val":11},{"a":9,"val":21},{"a":7,"val":31},{"a":8,"val":41}],[{"a":1,"val":12},{"a":9,"val":22},{"a":7,"val":32},{"a":8,"val":42}]]
Here's a solution using underscore:
var result = _.chain(data)
.map(item => _.map(item.val, val => ({a: item.a, val})))
.unzip()
.value();
var data = [
{a:1,val:[11,12]},
{a:9,val:[21,22]},
{a:7,val:[31,32]},
{a:8,val:[41,42]}
]
var result = _.chain(data)
.map( item => _.map(item.val, val => ({a: item.a, val})))
.unzip()
.value();
document.getElementById('result').textContent = JSON.stringify(result);<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.8.2/underscore.js"></script>
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