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2.1 KiB

Median accumulator

Simple, space-efficient algorithm to compute the median of an accumulation of elements.

  • Push-only (no running window)
  • Median is updated at each push (getting the median is always O(1))
  • Space-efficient: O(D) space, D being the number of different samples, not the total number of samples
  • Time-efficient: push is O(log(N))
  • Generic: T: Clone + Ord
  • Tested
  • No unsafe, no deps
  • no_std (optional): supports generic collections

Faster than other implementations if there are samples having the same value. If this is not your case, you should use another implementation.


use median_accumulator::*;

let mut acc = vec::MedianAcc::new();

assert_eq!(acc.get_median(), None);
assert_eq!(acc.get_median(), Some(MedianResult::One(7)));
assert_eq!(acc.get_median(), Some(MedianResult::Two(5, 7)));
assert_eq!(acc.get_median(), Some(MedianResult::One(7)));

If you ever encounter an unreachable panic, please file an issue or send me an e-mail.


Example with smallvec: (smallvec feature required)

use median_accumulator::*;

let mut acc = MedianAcc::<i32, smallvec::SmallVec<[(i32, u32); 64]>>::new();

For other collections than Vec or SmallVec, you must implement cc-traits and InsertIndex.


CopyLeft 2022-2023 Pascal Engélibert (why copyleft?)

This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, version 3 of the License.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License along with this program. If not, see