Generate Specific Float Array with Int range

Question

I would like to generate an Array with all Integers and .5 values with an Int Range. The result wanted :

min value = 0

max value = 5

generated Array = [0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5]

I know how to get only the integers value :

Array(0...5)

But not this one with float values ... I think is clear enough, anyone has an idea ?

Answer 1

Use Array() with stride(from:through:by:):

let arr = Array(stride(from: 0, through: 5, by: 0.5))
print(arr)

[0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0]

---

If your min and max values truly are Int, then you'll need to convert them to Double:

let min = 0
let max = 5
let step = 0.5

let arr = Array(stride(from: Double(min), through: Double(max), by: step))

---

Warning:

Due to the nature of floating point math, this can possibly lead to unexpected results if the step or endpoints are not precisely representable as binary floating point numbers.

@MartinR gave an example:

let arr = Array(stride(from: 0, through: 0.7, by: 0.1))
print(arr)

[0.0, 0.10000000000000001, 0.20000000000000001, 0.30000000000000004, 0.40000000000000002, 0.5, 0.60000000000000009]

The endpoint 0.7 was excluded because the value was slightly beyond it.

You might also want to consider using map to generate your array:

// create array of 0 to 0.7 with step 0.1
let arr2 = (0...7).map { Double($0) / 10 }

That will guarantee that you capture the endpoint 0.7 (well, a close approximation of it).

So, for your original example:

// create an array from 0 to 5 with step 0.5
let arr = (0...10).map { Double($0) / 2 }