7 stable releases
Uses old Rust 2015
1.2.4 | Aug 4, 2021 |
---|---|
1.2.3 | Mar 15, 2021 |
1.2.2 | Nov 21, 2019 |
1.2.1 | Jul 31, 2019 |
1.1.0 | Oct 17, 2018 |
#1777 in Data structures
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Used in 13 crates
(2 directly)
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PackedVec
A PackedVec
stores vectors of integers
efficiently while providing an API similar to Vec
. The basic idea is to store
each element using the minimum number of bits needed to represent every element
in the Vec
. For example, if we have a Vec<u64>
with elements [20, 30, 140],
every element wastes most of its 64 bits: 7 bits is sufficient to represent the
range of elements in the vector. Given this input vector, PackedVec
stores
each elements using exactly 7 bits, saving substantial memory. For vectors which
often contain small ranges of numbers, and which are created rarely, but read
from frequently, this can be a significant memory and performance win.
Examples
PackedVec
has two main API differences from Vec
: a PackedVec
is created
from a Vec
; and a PackedVec
returns values rather than references. Both
points can be seen in this example:
use packedvec::PackedVec;
let v = vec![-1, 30, 120];
let pv = PackedVec::new(v.clone());
assert_eq!(pv.get(0), Some(-1));
assert_eq!(pv.get(2), Some(120));
assert_eq!(pv.get(3), None);
assert_eq!(v.iter().cloned().collect::<Vec<_>>(), pv.iter().collect::<Vec<_>>());
Dependencies
~94–315KB