I want to know whether if an array is inside of a 2D array.
This is what I tried:
var x=[1,2];
var y=[[1,1],[1,2],[2,2],[3,3]];
y.includes(x); //should return true
2 Answers
you can create a hash:
var ar = [
[1,1],[1,2],[2,2],[3,3]
];
var hash = {};
for(var i = 0 ; i < ar.length; i += 1) {
hash[ar[i]] = i;
}
var val = [1,2];
if(hash.hasOwnProperty(val)) {
document.write(hash[val]);
}
2 Comments
tymeJV
Won't differentiate between
["1", "2"] and [1,2] - not sure if that matters for this case. +1 either way.
hackerrdave
Yea if we assume all values in the inner arrays will be integers and not strings then this is great solution!
You can do this with chained array methods!
var ar = [
[1,1],[1,2],[2,2],[3,3]
];
hasDuplicates(ar, [1,"1"]); //false
hasDuplicates(ar, [1,1]); //true
//Use some to determine at least 1 inner array matches
function hasDuplicates(array, valueToCheck) {
return array.some(function(a, i) {
//Check each inner arrays index, and verify that it equals on the same index of the array we want to check
return a.every(function(ax, ix) {
return valueToCheck[ix] === ax; //triple equals for equality!
})
});
}
[1,2] !== [1,2]so you can't directly compare them as objects_.findIndex(y, x)which would return the position insideyunderscorejs.org/#findIndex, or you could make it a truth test with_.findIndex(y,x) >== 0