I have the following 2D array
var items = [['al','bv','sd'],
['al','cc','ab'],
['cv','vv','sw'],
['al','bv','sd']
];
I need a function which will return me a similar array but with distinct values. For example, in the above array, ['al','bv','sd'] happens twice.
I would like the function to return me:
var items = [['al','bv','sd'],
['al','cc','ab'],
['cv','vv','sw']
];
Quick and dirty solution, assuming the data is small.
On each iteration, convert the row to a string. Use a dictionary to store the string with a value of True, if it is not already in the map. Also, add it to your output array. If it is already in the dictionary, go to the next item.
Example:
var d = {};
var out = [];
for( var i = 0; i < items.length; i++ ) {
var item = items[i];
var rep = item.toString();
if (!d[rep]) {
d[rep] = true;
out.push(item);
}
}
// out has the result
You have to loop two (or three times):
Loop again, through all "rows", from beginning to the end
Loop through all "columns":
.splice method.Code:
for (var i=0; i<items.length; i++) {
var listI = items[i];
loopJ: for (var j=0; j<items.length; j++) {
var listJ = items[j];
if (listI === listJ) continue; //Ignore itself
for (var k=listJ.length; k>=0; k--) {
if (listJ[k] !== listI[k]) continue loopJ;
}
// At this point, their values are equal.
items.splice(j, 1);
}
}
A simple sort and filter, function would do the trick.
var items = [
['al', 'bv', 'sd'],
['al', 'cc', 'ab'],
['cv', 'vv', 'sw'],
['al', 'bv', 'sd']
];
var temp = ''
var unique = items.sort().filter(r => {
if (r.join("") !== temp) {
temp = r.join("")
return true
}
})
console.log(unique);An unconventional but easier to code version
var items = [['al','bv','sd'],
['al','cc','ab'],
['cv','vv','sw'],
['al','bv','sd']
];
var temp = {};
for ( var i in items ) {
var serialized = JSON.stringify(items[i]);
if ( temp[serialized] ) {
items.splice( i, 1 );
continue;
}
temp[serialized] = true;
}
Try it here! http://jsfiddle.net/y3ccJ/1/
More conventional option:
var items = [['al','bv','sd'],
['al','cc','ab'],
['cv','vv','sw'],
['al','bv','sd']
];
var results = [];
loop: for ( var i in items ) {
compare: for ( var j in results ) {
for ( var k in items[i] ) {
if ( items[i][k] !== results[j][k] ) {
break compare;
}
}
continue loop;
}
results.push( items[i] );
}
If you can use lodash, this is good solution (note that based on your platform, the "require" keyword can differ, this is how to use it in Node.js):
var _ = require('lodash');
var objects = [['a', 'b', 'c'],['a'],['b', 'a', 'c']];
objects.forEach(innerArr => {
innerArr.sort();
});
console.log(_.uniqWith(objects, _.isEqual));
This would be output
[ [ 'a', 'b', 'c' ], [ 'a' ] ]
If order of elements in array matter to you, i.e. this array [ 'a', 'b', 'c' ] is considered different than this one ['b', 'a', 'c'], all you need is to delete the "sort" part :
var _ = require('lodash');
var objects = [['a', 'b', 'c'],['a'],['b', 'a', 'c'], ['a','b','c']];
console.log(_.uniqWith(objects, _.isEqual));
This would be output :
[ [ 'a', 'b', 'c' ], [ 'a' ], [ 'b', 'a', 'c' ] ]
You can do something like this :
var result = [];
result.push(items[0]);
for (i = 1; i < items.length; i++){
var ok;
for (j = 0; j < i; j++){
if (result[j].length != items[i].lenght) continue;
ok = false;
for (k = 0; k < items[i].length; k++) if (items[i][k] != result[j][k]) ok = true;
if (ok == false) break;
}
if (ok) result.push(items[i]);
}
return result;
function arrays_equal(a,b) { return !!a && !!b && !(a<b || b<a); }
Array.prototype.unique = function() {
var a = [];
for (var i = 0, l = this.length; i<l; i++) {
for (var j = i + 1; j < l; j++) if (arrays_equal(this[i], this[j])) j = ++i;
a.push(this[i]);
}
return a;
};
var ret = items.unique();
The demo.
Since this sounds like some sort of school assignment I will provide ideas not code. You should think about how a human looks through that 2D array and determines whether or not one of the arrays is unique or not. One has to look at each other row, for each row to determine if it is unique. Sounds like nested for loop to me ....
