Function tiles

pub fn tiles(
    size: usize,
    num_tilings: usize,
    floats: &[f64],
    ints: Option<&[isize]>,
) -> Vec<usize>

This function takes a series of floating point and integer values, and encodes them as tile indices using a provided size. This function is generally reserved for when you have extraordinarily large sizes that are too large for the IHT.

Arguments

• size—the upper bounds of all returned indices
• num_tilings—indicates the number of tile indices to be generated (i.e. the length of the returned Vec). This value hould be a power of two greater or equal to four times the number of floats according to the original implementation.
• floats—a list of floating-point numbers to be tiled
• ints—an optional list of integers that will also be tiled; all distinct integers will result in different tilings. In reinforcement learning, discrete actions are often provided here.

Return Value

The returned Vec<usize> is a vector containing exactly num_tilings elements, with each member being an index of a tile encoded by the function. Each member will always be >= 0 and <= size - 1.

Example

// find the indices of tiles for the point (x, y) = (3.6, 7.21) using 8 tilings and a maximum size of 1024:
let indices = tiles(1024, 8, &[3.6, 7.21], None);
 
// we get tiles all over the 1024 space as a direct result of the hashing
// instead of the more ordered indices provided by an IHT
assert_eq!(indices, vec![511, 978, 632, 867, 634, 563, 779, 737]);
 
// a nearby point:
let indices = tiles(1024, 8, &[3.7, 7.21], None);
 
// differs by one tile:
assert_eq!(indices, vec![511, 978, 632, 987, 634, 563, 779, 737]);
 
// and a point more than one away in any dim
let indices = tiles(1024, 8, &[-37.2, 7.0], None);
 
// will have all different tiles
assert_eq!(indices, vec![638, 453, 557, 465, 306, 526, 281, 863]);