如何使用 Ramda 表达式将包含 arrays 对象的数组转换为带有软管 object 的单个数组？

Question

I am having a difficult time, there is some bad mapping going on on my code.

I have an array containing array of objects like that:

[
   [{a: 1, b: 2},{a: 1, b: 3} ],
   [{a: 5, b: 2},{a: 2, b: 5}]
]

And I want to make like that:

[
   {a: 1, b: 2},
   {a: 1, b: 3},
   {a: 5, b: 2},
   {a: 2, b: 5}
]

In order to do that, I thought I found the magical solution, make things flat, using flatten function, it was not working ( this problem is just a piece of code in a lot of code ) and I was wondering why, i wasted some time to find that this the problem, it is not the behovior I am expecting, as you can see in the image, the first thing I have is an array containing an array having two objects, with flatten method, I was expecting an array of two objects, but I am getting what you see in the image:

The code I have ttried is this:

const expectedArray = R.flatten(myArrayOfArraysOfObjects);

Full example:

const singleTronconPoints = troncon => {
  return troncon.geometri_linestring;
};
console.log('troncons : ');
console.log(troncons);
console.log('map troncons points');
console.log(map(singleTronconPoints, troncons));
console.log('flatten');
console.log(flatten(map(singleTronconPoints, troncons)));

and this is full result:

How can I solve that, is there another magical (:P ) solution ( method ) to solve the problem?

Any help would be much appreciated.

Answer 1

Array.prototype.reduce() can also be an option:

const arr =[
  [{a: 1, b: 2},{a: 1, b: 3}],
  [{a: 5, b: 2},{a: 2, b: 5}]
]

const expectedArray = arr.reduce((acc, array) => {
  acc.push(...array);
  return acc;
}, []);

Answer 2

You can use array.flat

 let a = [ [{ a: 1, b: 2 }, { a: 1, b: 3 }], [{ a: 5, b: 2 }, { a: 2, b: 5 }] ]; let b = a.flat(); console.log(b)

Alternatively you can use reduce and inside callback use forEach and puch items from the nested array to accumulator array

 let a = [ [{ a: 1, b: 2 }, { a: 1, b: 3 }], [{ a: 5, b: 2 }, { a: 2, b: 5 }] ]; let b = a.reduce((acc, curr) => { curr.forEach(item => acc.push(item)) return acc; }, []); console.log(b)

Answer 3

use reduce() + push which faster flat() method.

refer this for to check performance. : https://jsbench.me/0ikcqa83ck/1

 let arr = [ [{a: 1, b: 2},{a: 1, b: 3} ], [{a: 5, b: 2},{a: 2, b: 5}] ] console.log(arr.flat()) let flattenArr = arr.reduce((acc, val) => (acc.push(...val),acc), []) console.log(flattenArr);

Answer 4

Array.flat is the magical solution you are looking for !

 var arr = [ [{a: 1, b: 2},{a: 1, b: 3} ], [{a: 5, b: 2},{a: 2, b: 5}] ] console.log(arr.flat())