Lua non-integer randomise

Question

I'm new at LUA and I need a help with code in using function math.random(...). The problem is if I need to generate integer values I just use

math.random(-1, 1) -- This is gonna be -1, 0 or 1. Profit.

But if I need non-integers between -1 and 0?

math.random(-1.0, 1.0) -- Still -1, 0 or 1. No profit.

I tried using this: -1.01, 1.01 but it is not gonna generate a number between values exactly I need.

How do I generate non-integer value between 1 and 0?

I think there's an error in your question, math.random() generates random values between 0 and 1. — poorandunlucky
– poorandunlucky, Commented Nov 23, 2019 at 23:02
@poorandunlucky yes I think I just forgot it, but I meant that I need to generate non-integer values for example between x and y variables, not just 1 and 0. — younyokel
– younyokel, Commented Nov 24, 2019 at 13:12

luther · Accepted Answer · 2019-11-22 16:25:28Z

6

Without arguments, math.random returns a floating-point number between 0 and 1. You can get other ranges by multiplying and adding:

math.random() * 2 - 1

Or more generally:

math.random() * (maximum - minimum) + minimum

answered Nov 22, 2019 at 16:25

luther

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3 Comments

younyokel Over a year ago

Hey, thanks for this! Is there a way I could limit fractions from the value I get with math.random() * (maximum - minimum) + minimum? For example if I use math.random(-1.1, 1.1) I'm getting only tenth from the value (x point y) or if I use math.random(-1.11, 1.11) I'm going to get the hundred from the value (x point yz). But using this I'm getting a very big fraction.

luther Over a year ago

Do you just need to round off the output, or do you really need a number that's right at a hundredth? Either way, that sounds like it should be a separate question.

younyokel Over a year ago

I guess you're right. Im just curious because the original way worked like this so it would be very useful.

Michael Duckham · Accepted Answer · 2019-11-25 14:53:01Z

1

You could also do something like math.random(-1, 1) + ( math.random(1, 99) / 100 ). Hopefully this helps a bit. math.random will only get whole numbers and integers. It won't return floats unfortunately.

answered Nov 25, 2019 at 14:53

Michael Duckham

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