How to manipulate the same element in multiple arrays

Question

I have a script on google sheets that calls an API and the response is an Array with multiple arrays, like this:

[[1,2,3], [4,5,6]...etc]

I'm trying to do something like trying to multiply the second element of each array by 2, while keeing the other elements. I have the whole array assigned to a variable but I can't figure out how to select the 2nd element of all arrays.

You don't need to select them all. You just need to loop over the outer array and then change the `[1]`st element — Taplar, Dec 14 '20 at 23:01
Look at [forEach()](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/forEach) or [`map()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/map) or see: [for-each-over-an-array-in-javascript](https://stackoverflow.com/questions/9329446/for-each-over-an-array-in-javascript) — pilchard, Dec 14 '20 at 23:02
`const yourArray = [[1,2,3], [4,5,6]]; for(let a of yourArray){ a[1] *= 2; }`. Of course, that will affect the original Arrays, so you might want to make a slice of the Arrays you don't want changed. — StackSlave, Dec 14 '20 at 23:19
Could you not just multiply each array by another variable set to [1,2,1]? — Erik Tyler, Dec 14 '20 at 23:28

score 3 · Accepted Answer · answered Dec 15 '20 at 00:22

3

Another solution using map:

 const arr = [[1,2,3], [4,5,6]];
 const farr = arr.map(r=>[r[0],r[1]*2,r[2]]);
 console.log(farr);

answered Dec 15 '20 at 00:22

Marios

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score 2 · Answer 2 · answered Dec 14 '20 at 23:30

Put a few columns of values on a spreadsheet. This function will put the same values right next to it with the second element in each row multiplied by two.

function multiply2ndElementOfEachRowBy2() {
  const ss=SpreadsheetApp.getActive();
  const sh=ss.getActiveSheet();
  const rg=sh.getRange(1,1,sh.getLastRow(),sh.getLastColumn());
  const arr=rg.getValues();
  arr.map(r=>{r[1]=r[1]*2;return r;}); 
  sh.getRange(1,sh.getLastColumn()+1,arr.length,arr[0].length).setValues(arr);
}

How to manipulate the same element in multiple arrays

2 Answers2