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iCAPs/packages/gspbox/3rdparty/flann/flann_build_index.m
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flann_build_index.m
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function [index, params, speedup] = flann_build_index(dataset, build_params)
%FLANN_BUILD_INDEX Builds an index for fast approximate nearest neighbors search
%
% [index, params, speedup] = flann_build_index(dataset, build_params) - Constructs the
% index from the provided 'dataset' and (optionally) computes the optimal parameters.
% Marius Muja, January 2008
algos = struct( 'linear', 0, 'kdtree', 1, 'kmeans', 2, 'composite', 3, 'kdtree_single', 4, 'hierarchical', 5, 'lsh', 6, 'saved', 254, 'autotuned', 255 );
center_algos = struct('random', 0, 'gonzales', 1, 'kmeanspp', 2 );
log_levels = struct('none', 0, 'fatal', 1, 'error', 2, 'warning', 3, 'info', 4);
function value = id2value(map, id)
fields = fieldnames(map);
for i = 1:length(fields),
val = cell2mat(fields(i));
if map.(val) == id
value = val;
break;
end
end
end
function id = value2id(map,value)
id = map.(value);
end
default_params = struct('algorithm', 'kdtree' ,'checks', 32, 'eps', 0.0, 'sorted', 1, 'max_neighbors', -1, 'cores', 1, 'trees', 4, 'branching', 32, 'iterations', 5, 'centers_init', 'random', 'cb_index', 0.4, 'target_precision', 0.9,'build_weight', 0.01, 'memory_weight', 0, 'sample_fraction', 0.1, 'log_level', 'warning', 'random_seed', 0);
if ~isstruct(build_params)
error('The "build_params" argument must be a structure');
end
params = default_params;
fn = fieldnames(build_params);
for i = [1:length(fn)],
name = cell2mat(fn(i));
params.(name) = build_params.(name);
end
if ~isnumeric(params.algorithm),
params.algorithm = value2id(algos,params.algorithm);
end
if ~isnumeric(params.centers_init),
params.centers_init = value2id(center_algos,params.centers_init);
end
if ~isnumeric(params.log_level),
params.log_level = value2id(log_levels,params.log_level);
end
[index, params, speedup] = nearest_neighbors('build_index',dataset, params);
if isnumeric(params.algorithm),
params.algorithm = id2value(algos,params.algorithm);
end
if isnumeric(params.centers_init),
params.centers_init = id2value(center_algos,params.centers_init);
end
end
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