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swaits aab55f58bb chore: repoint remaining links at git.swaits.com
Rewrites lingering github.com / *.sr.ht references to this Gitea instance,
translating GitHub and Sourcehut URL shapes to Gitea's (/blob/<ref>/ and
sr.ht /tree/<ref>/item/ -> /src/branch/<ref>/, /tree/<tag> -> /src/tag/<tag>,
/actions/workflows/X -> /actions?workflow=X, /edit/ -> /_edit/).

Left pointing at the old hosts on purpose: pull-request links (PRs were not
migrated), forks that were never migrated, and GitHub-only surfaces Gitea
lacks. OpenPGP identity proofs are untouched by design.
2026-08-31 18:32:20 -06:00

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# megapermute
A million permutation hypothesis test utility.
## Installation
1. If you don't already have rust installed, [install it](https://www.rust-lang.org/tools/install).
2. Then run: `cargo install --git https://git.swaits.com/swaits/megapermute`
## Usage
`megapermute` is a command-line utility which reads two input files,
`control.dat` and `treatment.dat`. Each is a text file containing a list of
numbers, treated internally as 64-bit floating point numbers.
- `control.dat`: the control sample
- `treatment.dat`: the treatment sample
With these two files in the current directory, running `megapermute` computes
the empircal difference in means and p-value for the null hypothesis, that H_0
is equivalent to H_a. You can think of p-value like the probability that the
null hypothesis is true.
### Example
Given the following two input files:
```bash
~/tmp
❯ bat control.dat
───────┬───────────────────────
│ File: control.dat
───────┼───────────────────────
1 │ 52
2 │ 104
3 │ 146
4 │ 10
5 │ 51
6 │ 30
7 │ 40
8 │ 27
9 │ 46
───────┴───────────────────────
~/tmp
❯ bat treatment.dat
───────┬───────────────────────
│ File: treatment.dat
───────┼───────────────────────
1 │ 94
2 │ 197
3 │ 16
4 │ 38
5 │ 99
6 │ 141
7 │ 23
───────┴──────────────────────
```
Running `megapermute` should yield results like this:
```bash
~/tmp
❯ megapermute
mu_control = 56.22222222222222
mu_treatment = 86.85714285714286
(mu_treatment - mu_control) = 30.63492063492064
p-value = 0.139556
```
## Performance
My goal with this was to take advantage of multiple cores by using
[`rayon`](https://crates.io/crates/rayon) iterators to compute the permutation
hypothesis test quickly. As of January 2022, this application can do one
million permutations on the example dataset listed above in 39.4 ms (N=69,
SD=2.6 ms), which is on the order of 25M permutations/second.
```bash
~/tmp
❯ hyperfine megapermute
Benchmark 1: megapermute
Time (mean ± σ): 39.4 ms ± 2.6 ms [User: 499.3 ms, System: 10.2 ms]
Range (min … max): 35.1 ms … 48.4 ms 69 runs
```
Benchmark machine info:
```bash
~/tmp
❯ neofetch
'c. stephenwaits@SWaits-Mac-01.local
,xNMM. --------------------------------
.OMMMMo OS: macOS 11.6.1 20G224 x86_64
OMMM0, Host: MacBookPro16,1
.;loddo:' loolloddol;. Kernel: 20.6.0
cKMMMMMMMMMMNWMMMMMMMMMM0: Uptime: 31 days, 21 hours, 23 mins
.KMMMMMMMMMMMMMMMMMMMMMMMWd. Packages: 149 (brew)
XMMMMMMMMMMMMMMMMMMMMMMMX. Shell: zsh 5.8
;MMMMMMMMMMMMMMMMMMMMMMMM: Resolution: 3840x2160, 1920x1080
:MMMMMMMMMMMMMMMMMMMMMMMM: DE: Aqua
.MMMMMMMMMMMMMMMMMMMMMMMMX. WM: Amethyst
kMMMMMMMMMMMMMMMMMMMMMMMMWd. Terminal: WezTerm
.XMMMMMMMMMMMMMMMMMMMMMMMMMMk CPU: Intel i9-9880H (16) @ 2.30GHz
.XMMMMMMMMMMMMMMMMMMMMMMMMK. GPU: Intel UHD Graphics 630, AMD Radeon Pro 5500M
kMMMMMMMMMMMMMMMMMMMMMMd Memory: 21514MiB / 32768MiB
;KMMMMMMMWXXWMMMMMMMk.
.cooc,. .,coo:.
```