Skip to main content

array-operations

Array operations — union, intersection, difference, symmetric difference — answer common data-cleanup questions. "What emails are in list A but not list B?" → difference. "What IDs appear in both?" → intersection. "All unique values across both lists?" → union. The ZTools Array Operations tool accepts two arrays (one item per line, or comma-separated, or JSON), runs the operation in the browser, and returns the result with counts. Case-sensitive or insensitive, trim-or-not, dedupe-or-keep-duplicates — all configurable.

Use cases​

Cross-reference user lists​

Marketing wants emails on List A but NOT on the unsubscribe list. Difference operation gives the answer instantly.

Find shared customers​

Two products, two CSVs of user IDs. Intersection shows users of both — your cross-sell candidates.

Spot drift in two configs​

Two YAML files list allowed origins. Symmetric difference reveals which entries are in one but not the other.

Validate a migration​

Old DB had 10,234 records. New DB has 10,233. Difference points to the one record that didn't migrate.

How it works​

  1. Paste list A and list B — One item per line, comma-separated, or JSON array. Tool auto-detects format.
  2. Pick operation — Union (A ∪ B), Intersection (A ∩ B), Difference (A − B), Symmetric Difference (A ⊕ B = items in exactly one).
  3. Configure matching — Case-sensitive (default), trim whitespace, treat numbers as numbers (so "1" matches 1).
  4. Read result — Output list plus counts: {input A: 1024, input B: 998, result: 76}. Copy as plain list or JSON.

Examples​

Input: A = [1,2,3,4]; B = [3,4,5,6]

Output: Union: [1,2,3,4,5,6]. Intersect: [3,4]. A−B: [1,2]. B−A: [5,6]. Symmetric: [1,2,5,6].

Input: A = emails subscribed; B = emails bounced

Output: A−B = clean recipients. Use this list for the next send.

Input: Case-insensitive intersection of "Alice" and "alice"

Output: [Alice] (or [alice] — picks first occurrence). Without case-insensitive matching, the result would be empty.

Frequently asked questions​

How big can the lists be?

Browser memory is the limit — 1 million items per side works fine in modern browsers. The Set data structure makes operations O(n).

Does order of inputs matter?

Union and intersection: no. Difference: yes — A−B differs from B−A.

What about duplicates within a list?

By default, treated as a set (deduplicated). Toggle "preserve duplicates" if you need multiset semantics (e.g. counting).

Does it support objects?

Primitive comparison only — strings, numbers, booleans. For objects, key on a stable property (id) and operate on that array.

Privacy?

All processing in the browser. Emails / IDs / customer data never leave your device.

Tips​

  • For very large lists, paste as JSON arrays — faster than line-splitting in the browser.
  • Trim whitespace by default — accidental trailing spaces are the #1 cause of "items don't match".
  • For approximate matching (fuzzy), use a fuzzy-search tool first to canonicalise, then array-op the cleaned lists.
  • Combine with the Find Duplicate Items tool when you need duplicates inside a single list, not across two.

Try it now​

The full array-operations runs in your browser at https://ztools.zaions.com/array-operations — no signup, no upload, no data leaves your device.

Open the tool ↗

Last updated: 2026-05-06 · Author: Ahsan Mahmood · Edit this page on GitHub