Comparing user array strings to list empty users

Question

I want a simple way to compare two arrays. One array has a list of emails and the other array is a list of emails who completed a form. I want to then return a list of people who have not completed the form. Here is the function I have, but it works pretty slow.

  function findMissingUsers() {
   var sheet = getSheet();    
   users = [array of all emails]; 
   completedUsers = [array of emails who completed form];

   users.forEach(function (row) {
    completedUsers.forEach(function (user) {
     if(row.Email != user.Username) {
      console.log(row);
     }
    });
   });
  }

Just trying to find a more efficient way of doing this.

Is the `completedUsers` array sorted or easily sortable? If so, you could try using a binary search of `completedUsers` instead of a sequential search and it should be `O(n log m)` unless I'm mistaken. — mcon, Dec 16 '15 at 22:10

score 1 · Answer 1 · edited May 23 '17 at 12:15

1

How about:

completedUsers.filter(function(n) {
    return users.indexOf(n) != -1
});

from here.

edited May 23 '17 at 12:15

Community

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1

answered Dec 16 '15 at 21:59

rphv

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Its an array of objects and not an array of email ids (string). – void Dec 16 '15 at 22:01
@void according to provided code both are arrays of emails. – scareddragon Dec 16 '15 at 22:02
@scareddragon I don't think. Look at this line `if(row.Email != user.Username) {` – void Dec 16 '15 at 22:03
@rphv, Moreover it does not improves the efficiency, Complexity will remain `O(n2)` – void Dec 16 '15 at 22:04
@void right, I was mistaken by those variables defs, where is written 'array of emails'. – scareddragon Dec 16 '15 at 22:06

score 0 · Answer 2 · answered Dec 16 '15 at 22:01

0

You can use e.g. lodash library and _.difference function. Details here.

answered Dec 16 '15 at 22:01

scareddragon

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score 0 · Answer 3 · answered Dec 16 '15 at 22:12

0

You can do it like this:

var incompletedUsers = users.filter(function(user){
    return completedUsers.every(function(completedUser){
        return user.Email !== completedUser.Username;
    });
});

answered Dec 16 '15 at 22:12

Johan Karlsson

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Comparing user array strings to list empty users

3 Answers3