Created
July 6, 2022 03:10
-
-
Save lululombard/15edc5e8550893cda283a0c38cba9d56 to your computer and use it in GitHub Desktop.
Piecewise linear interpolation in C++
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
#include <iostream> | |
#include <map> | |
using namespace std; | |
float piecewise_linear_interpolate(map<float, float> value_mappings, float input); | |
int main() { | |
map<float, float> voltage_to_percent_mapping { | |
{ 09.5, 0.0 }, | |
{ 10.8, 1.00 }, | |
{ 12.8, 10.00 }, | |
{ 12.9, 20.00 }, | |
{ 13.0, 30.00 }, | |
{ 13.1, 40.00 }, | |
{ 13.2, 70.00 }, | |
{ 13.3, 90.00 }, | |
{ 13.4, 99.00 }, | |
{ 13.5, 100.00 } | |
}; | |
cout << piecewise_linear_interpolate(voltage_to_percent_mapping, 12.56) << endl; | |
return 0; | |
} | |
float piecewise_linear_interpolate(map<float, float> m, float input) { | |
// Out of bounds (too low) | |
if (input < m.begin()->first) { | |
return m.begin()->second; | |
} | |
// Out of bounds (too high) | |
if (input > m.rbegin()->first) { | |
return m.rbegin()->second; | |
} | |
// Find the two nearest values and interpolate between them | |
for (auto it = m.begin(); it != m.end(); ++it) { | |
if (input > it->first && input < next(it)->first) { | |
float x1 = it->first; | |
float y1 = it->second; | |
float x2 = next(it)->first; | |
float y2 = next(it)->second; | |
float slope = (y2 - y1) / (x2 - x1); | |
float y_intercept = y1 - (slope * x1); | |
return (slope * input) + y_intercept; | |
} | |
} | |
// Fallback (should never happen) | |
return 0.0; | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment