Delete a list of columns in a 2d array using java script

Question

I need to delete some columns in a 2d array. The list is named as hiddenCols

var array = [
  ["a", "b", "c"],
  ["a", "b", "c"],
  ["a", "b", "c"]
]

hiddenCols = [3, 1] // these are pos and not indexes
for (var j = 0; j < array.length; j++) {
  for (var i = 0; i < hiddenCols.length; i++) {

    array[j].splice(hiddenCols[i], hiddenCols[i])
  }
}
console.log(JSON.stringify(array));

The expected result is var array = [["b"],["b"],["b"]];

for (var j = 0; i < array.length; i++) { the variable j is declared as a loop variable but i is used in the check for termination. — VLAZ
– VLAZ, Commented Jan 20, 2021 at 13:54

prasanth · Accepted Answer · 2021-01-20 13:58:34Z

1

You could do with Arrya#reduce

const arr = [["a", "b", "c"],["a", "b", "c"],["a", "b", "c"]];
const hiddenCols = [3, 1];

let result = arr.reduce((acc, item) => {
  let res = item.filter((_, ind) => hiddenCols.indexOf(ind + 1) == -1);
  acc.push(res)
  return acc;
}, [])

console.log(result);

edited Jan 20, 2021 at 13:58

answered Jan 20, 2021 at 13:56

prasanth

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2 Comments

pilchard Over a year ago

No need for reduce() since you're returning an array of the same length simply use map()

prasanth Over a year ago

@pilchard yes.. but someone already posted. And this also one of the method right then why down-voted

Ori Drori · Accepted Answer · 2021-01-20 14:00:19Z

1

Use Array.map() to iterate the rows, and filter the items by checking that the position is not included in hiddenCol:

const arr = [["a", "b", "c"],["a", "b", "c"],["a", "b", "c"]]

const hiddenCols = [3, 1]
const result = arr.map(item =>
  item.filter((_, ind) => !hiddenCols.includes(ind + 1))
)

console.log(result)

answered Jan 20, 2021 at 14:00

Ori Drori

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