DifferentialEvolution::DifferentialEvolution()
: PopulationBasedOptimisationAlgorithm() {
setInitialisingFunctions({{
[this](
const arma::uword numberOfDimensions_,
const arma::mat& initialParameters_) {
population_ = initialParameters_;
return initialParameters_;
},
"Population initialisation"
},
{ [this](
const arma::uword numberOfDimensions_,
const arma::mat& initialParameters_) {
localBestObjectiveValues_.set_size(populationSize_);
localBestObjectiveValues_.fill(std::numeric_limits<double>::infinity());
return initialParameters_;
},
"Local best objective values initialisation"
}
});
setNextParametersFunctions({{
[this](
const arma::uword numberOfDimensions_,
const arma::mat& parameters_,
const arma::rowvec& objectiveValues_,
const arma::rowvec& differences_) {
for (arma::uword n = 0; n < populationSize_; ++n) {
if (objectiveValues_(n) < localBestObjectiveValues_(n)) {
population_.col(n) = parameters_.col(n);
}
}
arma::mat populationCandidates(arma::size(population_));
for (arma::uword n = 0; n < populationSize_; ++n) {
arma::uvec randomIndices = randomPermutationVector(populationSize_, 3);
populationCandidates.col(n) = population_.col(randomIndices(0)) + scalingFactor_ * (population_.col(randomIndices(1)) - population_.col(randomIndices(2)));
}
return populationCandidates;
},
"Differential evolution"
}
});
setScalingFactor(0.5);
}
static OSStatus MakeImageDocument(CFURLRef url, CFStringRef imageType, const ExportInfo *exportInfo)
{
OSStatus err = noErr;
CGContextRef c = NULL;
CGImageRef image;
Boolean useDisplayColorSpace;
// First make a bitmap context for a US Letter size
// raster at the requested resolution.
int dpi = exportInfo->dpi;
size_t width = (size_t)(8.5*dpi), height = (size_t)11*dpi;
// For JPEG output type the bitmap should not be transparent. If other types are added that
// do not support transparency, this code should be updated to check for those types as well.
Boolean needTransparentBitmap =
!(CFStringCompare(imageType, kUTTypeJPEG, kCFCompareCaseInsensitive) == kCFCompareEqualTo);
// Create an RGB Bitmap context using the generic calibrated RGB color space
// instead of the display color space.
useDisplayColorSpace = false;
c = createRGBBitmapContext(width, height, useDisplayColorSpace,
needTransparentBitmap);
if(c == NULL){
fprintf(stderr, "Couldn't make destination bitmap context!\n");
// Users of this code should update this to be an error code they find useful.
return memFullErr;
}
// Scale the coordinate system based on the resolution in dots per inch.
CGContextScaleCTM(c, dpi/72, dpi/72);
// Set the font smoothing parameter to false since it's better to
// draw any text without special LCD text rendering when creating
// rendered data for export.
if(CGContextSetShouldSmoothFonts != NULL)
CGContextSetShouldSmoothFonts(c, false);
// Set the scaling factor for shadows. This is a hack so that
// drawing code that needs to know the scaling factor can
// obtain it. Better would be that DispatchDrawing and the code
// it calls would take this scaling factor as a parameter.
setScalingFactor(dpi/72);
// Draw into that raster...
DispatchDrawing(c, exportInfo->command);
// Set the scaling factor back to 1.0.
setScalingFactor(1.0);
// Create an image from the raster data. Calling
// createImageFromBitmapContext gives up ownership
// of the raster data used by the context.
image = createImageFromBitmapContext(c);
// Release the context now that the image is created.
CGContextRelease(c);
c = NULL;
if(image == NULL){
// Users of this code should update this to be an error code they find useful.
return memFullErr;
}
// Now export the image.
if(exportInfo->useQTForExport)
exportCGImageToFileWithQT(image, url, imageType, exportInfo->dpi);
else
exportCGImageToFileWithDestination(image, url, imageType, exportInfo->dpi);
CGImageRelease(image);
return err;
}
