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https://github.com/martinmoene/clamp
Limit a value or a range of values to fall between two extremes
https://github.com/martinmoene/clamp
Last synced: 16 days ago
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Limit a value or a range of values to fall between two extremes
- Host: GitHub
- URL: https://github.com/martinmoene/clamp
- Owner: martinmoene
- License: other
- Created: 2014-03-05T09:25:34.000Z (almost 11 years ago)
- Default Branch: master
- Last Pushed: 2015-06-27T16:41:23.000Z (over 9 years ago)
- Last Synced: 2024-10-28T03:20:55.629Z (2 months ago)
- Language: C++
- Homepage:
- Size: 289 KB
- Stars: 4
- Watchers: 3
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
Clamp algorithm [](https://travis-ci.org/martinmoene/clamp)
===============
A simple algorithm to limit a value or a range of values to fall between two extremes. `clamp` has been proposed for the C++ `` library under document number [N4536](http://open-std.org/JTC1/SC22/WG21/docs/papers/2015/n4536.html).
Code to limit a value between two extremes can come by various guises.
From what we found normal some (a long) time ago:
```
int clampedValue = value;
if ( value < minValue ) clampedValue = minValue;
[else] if ( value > maxValue ) clampedValue = maxValue;
```
via:
```
const int clampedValue = std::min( std::max( value, minValue ), maxValue );
```
to:
```
const int clampedValue = clamp( value, minValue, maxValue );
```
`clamp()` already exists in C++ libraries such as Boost[1] and Microsoft AMP[2]. This proposal is inspired on the Boost version by Marshall Clow. There are also still plenty programming language systems that do not provide it, such as C#, Java, PHP, Python (although numpy has `clip()`), Ruby [3].
Usage
-----
Clamp a single value implicitly using `std::less<>`:
```
constexpr auto v = clamp( 7, 3, 9 );
```
Note: std::less<>::operator() will become constexpr in C++14.
Clamp a single value using the given predicate:
```
constexpr auto v = clamp( 7, 3, 9, std::less() );
```
Clamp a range of values implicitly using `std::less<>`:
```
std::vector a{ 1,2,3,4,5,6,7,8,9 };
auto out = clamp_range( a.begin(), a.end(), a.begin(), 3, 7 );
```
Clamp a range of values using the given predicate:
```
std::vector a{ 1,2,3,4,5,6,7,8,9 };
auto out = clamp_range( a.begin(), a.end(), a.begin(), 3, 7, std::less<>() );
```
Note: std::less<> defaults to void and provides a templated member operator()() in C++14.
Names
-----
Other names for `clamp_range()` could be `clamp_elements()`, or `clamp_transform()`.
Note and references
-------------------
[1] `clamp()` in the [Boost Algorithm](http://www.boost.org/libs/algorithm/doc/html/algorithm/Misc.html#the_boost_algorithm_library.Misc.clamp) library.
[2] Microsoft. [C++ Accelerated Massive Parallelism](http://msdn.microsoft.com/en-us/library/hh265137.aspx) library.
[3] Try: http://stackoverflow.com/search?q=clamp
[4] Implementation note. Why does the implementation of `std::max()` in the GNUC `` library use `if()` instead of the ternary operator `?:` ? Jonathan Wakely answers: That code dates back to the SGI STL. It was changed, but then reverted, you can read the saga at http://gcc.gnu.org/ml/libstdc++/2012-09/msg00128.html