Remove duplicate substring in an array

Question

I have an array like below:

[
  'author/2020/01/01/all_authors_000.csv',
  'book/2020/01/01/all_books_000.csv',
  'book/2020/01/01/all_books_001.csv',
  'book/2020/01/01/all_books_002.csv',
  'others/2020/01/01/other_stuff.csv',
]

As you can see there are three items that start with the word book. I want to remove all but one, so I end up with something like:

[
  'author/2020/01/01/all_authors_000.csv',
  'book/2020/01/01/all_books_000.csv',
  'others/2020/01/01/other_stuff.csv',
]

How can I achieve this?

Technically your question says Remove duplicate substring in an array and there is no duplicate. — Manas Khandelwal
– Manas Khandelwal, Commented Mar 22, 2021 at 7:25
what is the criteria. are book/2020 and book/2021 also dublicates? — eamanola
– eamanola, Commented Mar 22, 2021 at 7:32

David Malášek · Accepted Answer · 2021-03-22 07:37:51Z

3

Here is working example:

var array = [
   "author/2020/01/01/all_authors_000.csv",
   "book/2020/01/01/all_books_000.csv",
   "book/2020/01/01/all_books_001.csv",
   "book/2020/01/01/all_books_002.csv",
   "others/2020/01/01/other_stuff.csv",
];

var filteredArray = [];
var previous = "";

for (let i of array) {
   if (i.substr(0, i.indexOf("/")) != previous) {
      filteredArray.push(i);
      previous = i.substr(0, i.indexOf("/"));
   }
}

Every loop the value before "/2020" is stored inside the previous variable, and the if statement checks, if the value is the same as in the previous loop. If not, it pushes it into the filteredArray.

Therefore filteredArray is the array without duplicates.

edited Mar 22, 2021 at 7:37

answered Mar 22, 2021 at 7:33

David Malášek

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2 Comments

blankface Over a year ago

thank you. do you know if this can also be achieved by lodash?

David Malášek Over a year ago

@blankface I don't have experience with lodash myself, but take a look at this.

Behemoth · Accepted Answer · 2021-03-22 07:57:02Z

0

Here is another method of doing it. Basically a function that takes in your array and a criteria to identify duplicates (in your case book). All of these duplicates will be removed but the first one.

const array = [
  "author/2020/01/01/all_authors_000.csv",
  "book/2020/01/01/all_books_000.csv",
  "book/2020/01/01/all_books_001.csv",
  "book/2020/01/01/all_books_002.csv",
  "others/2020/01/01/other_stuff.csv",
];

const removeDuplicates = (array, criteria) => {
  return array.filter(
    (path) =>
      ![...array.filter((path) => path.includes(criteria)).splice(1)].includes(
        path
      )
  );
};

console.log(removeDuplicates(array, "book"));

answered Mar 22, 2021 at 7:57

Behemoth

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