Lodash typescript – Combining multiple arrays into a single one and perform calculation on each

I have a Record<string, number[][]> and trying to perform calculation over these values.

An example input:

   const input1 = {
      key1: [
        [2002, 10],
        [2003, 50],
      ],
    };
    const input2 = {
      key1: [
        [2002, 20],
        [2003, 70],
      ],
    };
    const input3 = {
      key1: [
        [2002, 5],
        [2003, 60],
      ],
    };

For each key, and for the specific year I want to do the following

year => input1 + input2 - input3
// output: 2002 => 25, 2003 => 60

For this I have been playing around with lodash/fp.

map(a => a.map(nth(1)))(map('key1')([input1, input2]))
// [[10, 50], [20, 70], [5, 60]]

is there a way to somehow pass the inputs and iterate over them, and somehow get a callback function to get the values to perform the calculation.

I tried zip, zipWith but didn’t get to anywhere with them.

Any clue what I can do in this instance?

Thank you for your help.

Answer

You could get an object with _.fromPairs method and then use _.mergeWith to add and subtract.

const input1 = {
  key1: [
    [2002, 10],
    [2003, 50],
  ],
};
const input2 = {
  key1: [
    [2002, 20],
    [2003, 70],
  ],
};
const input3 = {
  key1: [
    [2002, 5],
    [2003, 60],
  ],
};


const [one, two, three] = _.map([input1, input2, input3], ({key1 }) => _.fromPairs(key1))
const add = _.mergeWith(one, two, (a, b) => a + b)
const sub = _.mergeWith(add, three, (a, b) => a - b)

console.log(add)

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