How do I round numbers up on LUA script?

[Alistair]

Its probably a bit stupid, I mean - in the editor theres probably a button saying "tO rOuNd uP nUmBeRs pReSs tHe bIg rEd bUtToN tHaT sAyS rOuNd uP" but I am making an LUA script right now that displays two things - time and speed. The numbers are a really long, seemingly endless decimal and i am using a 2 x 2 monitor. Does anyone know how to solve this? Thanks :D

[Unit 744]

I know math.floor() will simply truncate. There is probably a better built-in function for rounding, but you could pretty easily write your own function that checks a decimal; if it is 0.5 or greater, math.floor()+1, otherwise just math.floor().

Using math.floor will remove all the decimals when displaying too. If you want to only display a set number of decimals (say, two digits after the decimal), you can do the following:

math.floor(x*100)/100

this will display two digits after the decimal. Replace 100 with the desired number of digits after the decimal (10 for 1 after, 1000 for 3 after, etc.). If it makes more sense, math.floor(x*1)/1 displays 0 digits after the decimal.

Hope this helps.

[yungmono]

For me I would write:


screen.drawText( x, y, 'Speed:'..string.format('%.0f', speed))


%.0f= no decimal place
%.1f= 1 decimal place
%.2f= 2 decimal place
etc
Hope this helps you

[Alistair]

Thanks Everyone :D I will take all this information to make an easy to use interface

[Ra-Ra-Rasputin]

You can also do X = X - ( X % 1 ) to simply snip off the decimals completely if you're not interested in actual rounding.

[Alistair]

I am finding it quite hard to understand this (yes I know I am stupid lol) . Here is my current script - if anyone could reply telling me what I need to add and where that would be helpful. I appreciate all the feedback :D


function onTick()
input.getNumber(1)
input.getNumber(2)
end

function onDraw()
w = screen.getWidth(32)
h = screen.getHeight(32)
screen.setColor(255, 0, 0) -- Red
screen.drawText(2, 2, "Time:")
screen.drawText(2, 10, "Speed:")
end

:D

[DanDanAttack]

math.ceil(x)

https://pgl.yoyo.org/luai/i/math.ceil

[Ra-Ra-Rasputin]

Ceiling is just the opposite of floor though. It rounds 10.00000000000000001 to 11.

[ElfBossHogg]

For rounding you can use the following...

math.floor(x+0.5)

If the 10th's part of number is less then 0.5 then floor will always put it to the "low". If it's over the adding 0.5 will roll it and floor will make it the "high"

For example... rounding 10.3 should be 10
math.floor(10.3+0.5)=math.floor(10.8) = 10

rounding 10.8.. should be 11
math.floor(10.8+0.5)=math.floor(11.3)=11

Now for rounding up...
SOLUTION: math.floor(x+1)

x+1 will always put you in to the "next set" which when floored will bring you to the start of the next set.. which is the round up.

If x=0.1 then round up = 1...
math.floor(0.1+1)=math.floor(1.1)=1

if x=1.9 round up would be 2...
math.floor(1.9+1)=math.floor(2.9)=2

if x=198.85 then round up = 199
math.floor(198.85+1) = math.floor(199.95)= 199

NOTE: This will only work for positive numbers.

[Ra-Ra-Rasputin]

ElfBossHogg hits in with the 200 IQ play. Yeah, that absolutely will work

[DanDanAttack]

Originally posted by Ra-Ra-Rasputin:

Ceiling is just the opposite of floor though. It rounds 10.00000000000000001 to 11.

Yep. But it’s simple enough for what this guy wants.

[Jorg Hammond]

If one does not care about rounding the last decimal but just about the display, the easiest way appears to me to be the string format one which yungmono described.

[ElfBossHogg]

Originally posted by DanDanAttack:

Originally posted by Ra-Ra-Rasputin:

Ceiling is just the opposite of floor though. It rounds 10.00000000000000001 to 11.

Yep. But it’s simple enough for what this guy wants.

Yep... actually I think it may be exactly what he needs right out of the box.

math.floor(x+1) will give the exact same result as math.ceil(x). Math Ceiling is the rounds up which is what the op was asking for.

[Alistair]

OK I have one more stupid question. Where in my script should I put all these? :D

[Ra-Ra-Rasputin]

Where-ever you want the number to be rounded :)
You can either round the number directly on assignment, which means you only round it once (optimized), but this is really bad if you use the number to control something, like balance.

Your other option is to round it only when it needs to be rounded e.g. when you display it on screen.

[Alistair]

Originally posted by Ra-Ra-Rasputin:

Where-ever you want the number to be rounded :)
You can either round the number directly on assignment, which means you only round it once (optimized), but this is really bad if you use the number to control something, like balance.

Your other option is to round it only when it needs to be rounded e.g. when you display it on screen.

:D Thanks