CODEWITHSUNDEEP
iphoneobjective-cios5
KTas
KTas

Reputation: 449

Objective c map one number range to another

Hi I am wanting to map a particular range of numbers to a different range in objective C for an iPad application.

For example I may have an input value in the range 0-255 but I want to output to be in the range 0.5-1. For example, an input of 127.5 would result in an output of 0.75.

Cheers in advance.

Upvotes: 2

Views: 1512

Answers (2)

Nick Forge
Nick Forge

Reputation: 21464

Here's the general solution (it should work for any combination of ranges and input values):

CGFloat const inMin = 0.0;
CGFloat const inMax = 255.0;

CGFloat const outMin = 0.5;
CGFloat const outMax = 1.0;

CGFloat in = 127.5;
CGFloat out = outMin + (outMax - outMin) * (in - inMin) / (inMax - inMin);

Upvotes: 9

theory
theory

Reputation: 9887

Calculate the ratio of the first and apply it to the range of the second:

CGFloat result = ((127.5 / 255) * 0.5) + 0.5;

Upvotes: 5

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