How to get number of occurrences in an array in array? Javascript-CodePudding

In JavaScript, I want to count the number of times "N" in is in the first, second, third, fourth column. I want each other there values. I want to get the number of occurrences in an array in array, and then get four numbers equal the occurrences.

input:

var set =[
['N', 'N', 'Y', 'N'],
['1', 'N', '2', 'N'],
['N', '1', '4', 'N'],
['2', 'N', 'N', '1']]

output: 3 2 2 2

CodePudding user response：

const set = [
  ['N', 'N', 'Y', 'N'],
  ['1', 'N', '2', 'N'],
  ['N', '1', '4', 'N'],
  ['2', 'N', 'N', '1'],
];
const countNs = row => row.reduce((acc, curr) => acc   (curr === 'N' ? 1 : 0), 0);
// number of Ns in each row
console.log(set.map(countNs));
const transpose = a => a[0].map((_, c) => a.map(r => r[c]));
// Number of Ns in each column
console.log(transpose(set).map(countNs));

CodePudding user response：

var set =[
['N', 'N', 'Y', 'N'],
['1', 'N', '2', 'N'],
['N', '1', '4', 'N'],
['2', 'N', 'N', '1']];

let output = [];
set.forEach(array=>{
let count = 0;
  array.forEach(letter =>{
    if (letter === "N"){
      count  
    }
  })
  output.push(count);
})

console.log(output);

//if you want to count by column
output = [0,0,0,0];
set.forEach(array=>{
  for(let a=0;a<array.length;a  ){
    if (array[a] === "N"){
      output[a]  
    }
  }
})

console.log(output);

loop through your outer array passing each array into the function....then loop the the innerArray and check if the letter is "N" ....if so...increment count.....then push to the output array