Java中带有1D数组的锯齿状多维数组的明智筛选

Question

 const Amaths = [ [1, 2, 3, 5, 6, 7, 8], [4, 5, 6, 8], [12, 3, 4] ] const checks = [2.5, 4.01, 5]; const picks = []; for (let j = 0; j < Amaths.length; j++) { for (let k = 0; k < Amaths[j].length; k++) { if (Amaths[j][k] > checks[j]) { picks.push(Amaths[j][k]); } } } console.log("picks", picks) 

I want to filter a jagged multidimensional array element-wis without flattening the output array; in this example, "picks".

I have tried using a for loop but the output, "picks", is flattened. Also, I have used mathjs library function, but it seems the element-wise arithmetic operations in this library only works for non-jagged multidimensional arrays.

The expected result should be:

 const picks = [ [3, 5, 6, 7, 8], [5, 6, 8], [12] ] console.log ("expected picks", picks) 

Answer 1

Use .map to transform into another 2d array, calling .filter on each subarray while comparing against the checks at the index of the subarray being iterated over:

 const Amaths = [ [1, 2, 3, 5, 6, 7, 8], [4, 5, 6, 8], [12, 3, 4] ] const checks = [2.5, 4.01, 5]; const result = Amaths.map( (subarr, i) => subarr.filter( num => num >= checks[i] ) ); console.log(result); 

To fix your original code, you'd have to push a new subarray to picks on every outer iteration:

 const Amaths = [ [1, 2, 3, 5, 6, 7, 8], [4, 5, 6, 8], [12, 3, 4] ] const checks = [2.5, 4.01, 5]; const picks = []; for (let j = 0; j < Amaths.length; j++) { picks.push([]); for (let k = 0; k < Amaths[j].length; k++) { if (Amaths[j][k] > checks[j]) { picks[j].push(Amaths[j][k]); } } } console.log("picks", picks) 

(but array methods are probably a much better choice here, they're a lot more concise and easy to understand)