How to Hash / Checksum in a spreadsheet

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DaveT1
Posts: 227
Joined: 07 Oct 2014, 11:23

How to Hash / Checksum in a spreadsheet

Post by DaveT1 » 19 Apr 2023, 15:03

Hi,

Hope this is appropriate (place) to ask this...

I have a column of numbers in a spreadsheet (LO Calc as it happens). I want to check that this column of numbers, and the precise order of them, are unique. This is because I'll have many such columns of numbers and I want to check that I don't indvertently duplicate them.

One approach is illustrated in the image (where the column of numbers I want to test for uniqueness is column headed 'operations'):

image.png
image.png (54.78 KiB) Viewed 1549 times

Here, the final number in the bottom-right cell will be a 'prime-hash' (loose terminology). It = the multiplication of all (Prime^operation)_i * (Prime^operation)_(i+1) *..., etc, etc - where i is the first row in the table.

It does give unique 'prime-hash' values, but it blows up pretty quickly. So it's not suitable for my current needs.

So is there a relatively simple way to implement a hash-checksum-like operation in a spreadsheet? I wouldn't mind if it flagged up a small number of false-positives 'cos I could check these manually.

Anyway, just looking for some thoughts or pointers.

Much appreciated.
mcl
Posts: 387
Joined: 04 May 2018, 16:35

Re: How to Hash / Checksum in a spreadsheet

Post by mcl » 25 Apr 2023, 00:38

DaveT1 wrote: I want to check that this column of numbers, and the precise order of them, are unique.
Probably I'm missing the point, but can it be solved with conditional formatting and filters?
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