treez

A collection of useful data structures

segment tree

implementation: array based

todo: generic type

notes: for static use after initialization

```rust

let mut segments = vec![]; for i in 0..10 { let n = (i5, 5i+5, i); //(leftbound,rightbound,segment_id); inclusive bounds segments.push( n ); }

let t : treez::seg::TreeSeg = treez::seg::TreeSeg::init( segments.asslice() ); let querysegs: HashSet<_> = t.getsegsfrom_bound( (15,20) ).iter().cloned().collect();

let check: HashSet<_> = [ 2, 3, 4 ].iter().cloned().collect(); println!( "query segs: {:?}", querysegs ); assert!( check.intersection(&querysegs).count() == check.len() );

```

red black tree

implementation: array based, threshold compaction, minimal heap allocation

todo: optimize internal representation and operations, generic type

notes: comparable performance to BTreeMap

```rust

let mut t = treez::rb::TreeRb::new(); for i in 0..nums.len() { let r = nums[i]; t.insert( r, i as isize ); }

for i in 0..nums.len() { let r = nums[i]; let v = t.remove( &r ).expect( "remove unsuccessful" ); }

```

reverse automatic gradient differentiation

implementation: array based, scalar variable

todo: vectorize operations instead of scalars, add more test coverage, tweek to more ergonomic interface

```rust

let mut c : autograd::Context = Default::default();

//setup variables let mut buf = { let mut x = autograd::initvar( & mut c, 6f64 ); let mut y = autograd::initvar( & mut c, 7f64 ); let mut z = autograd::initop( & mut c, autograd::OpType::Mul, & mut [ & mut x, & mut y ] ); let mut a = autograd::initvar( & mut c, 3f64 ); let b = autograd::init_op( & mut c, autograd::OpType::Add, & mut [ & mut z, & mut a ] ); vec![ x, y, z, a, b ] };

let varids = autograd::fwdpass( & mut c, & mut buf ).unwrap();

let mut varmap = HashMap::new(); for i in [ "x", "y", "z", "a", "b" ].iter().zip( varids ) { var_map.insert( i.0, i.1 ); }

//compute gradient of b with respect to every other variable let mut vargrad = HashMap::new(); let bindex = *varmap.get(&"b").unwrap(); for i in varmap.iter() { let grad = autograd::computegrad( & mut c, bindex, *i.1 ).unwrap(); var_grad.insert( *i.0, grad ); }

assert!( *vargrad.get(&"b").unwrap() == 1f64 ); assert!( *vargrad.get(&"a").unwrap() == 1f64 ); assert!( *vargrad.get(&"z").unwrap() == 1f64 ); assert!( *vargrad.get(&"x").unwrap() == 7f64 ); assert!( *var_grad.get(&"y").unwrap() == 6f64 );

```