?? svmsim.m
字號:
function Yd = svmSim(svm,Xt)
% ------------------------------------------------------------%
cathe = 10e+6; % kernel輸出的元素個數的上限
nx = size(svm.x,2); % 訓練樣本數
nt = size(Xt,2); % 測試樣本數
block = ceil(nx*nt/cathe); % 分塊處理
num = ceil(nt/block); % 每塊測試樣本數
for i = 1:block
if (i==block)
index = [(i-1)*num+1:nt];
else
index = (i-1)*num+[1:num];
end
Yd(index) = svmSim_block(svm,Xt(:,index)); % 測試輸出
end
% ------------------------------------------------------------%
function Yd = svmSim_block(svm,Xt);
% 輸入參數:
% svm 支持向量機(結構體變量)
% the following fields:
% type - 支持向量機類型 {'svc_c','svc_nu','svm_one_class','svr_epsilon','svr_nu'}
% ker - 核參數
% type - linear : k(x,y) = x'*y
% poly : k(x,y) = (x'*y+c)^d
% gauss : k(x,y) = exp(-0.5*(norm(x-y)/s)^2)
% tanh : k(x,y) = tanh(g*x'*y+c)
% degree - Degree d of polynomial kernel (positive scalar).
% offset - Offset c of polynomial and tanh kernel (scalar, negative for tanh).
% width - Width s of Gauss kernel (positive scalar).
% gamma - Slope g of the tanh kernel (positive scalar).
% x - 訓練樣本
% y - 訓練目標;
% a - 拉格朗日乘子%
% Xt 測試樣本,d×n的矩陣,n為樣本個數,d為樣本維數
% 輸出參數:
% Yd 測試輸出,1×n的矩陣,n為樣本個數,值為+1或-1
% ------------------------------------------------------------%
type = svm.type;
ker = svm.ker;
X = svm.x;
Y = svm.y;
a = svm.a;
% ------------------------------------------------------------%
% 測試輸出
epsilon = 1e-8; % 如果小于此值則認為是0
i_sv = find(abs(a)>epsilon); % 支持向量下標
switch type
case 'svc_c',
tmp = (a.*Y)*kernel(ker,X,X(:,i_sv)); % 行向量
b = Y(i_sv)-tmp;
b = mean(b);
tmp = (a.*Y)*kernel(ker,X,Xt);
tmp = tmp+b;
Yd = sign(tmp);
case 'svc_nu',
%------------------------------------%
% 與 'svc_c' 情況相同
tmp = (a.*Y)*kernel(ker,X,X(:,i_sv)); % 行向量
b = Y(i_sv)-tmp;
b = mean(b);
tmp = (a.*Y)*kernel(ker,X,Xt);
Yd = sign(tmp+b);
case 'svm_one_class',
n_sv = length(i_sv);
tmp1 = zeros(n_sv,1);
for i = 1:n_sv
index = i_sv(i);
tmp1(i) = kernel(ker,X(:,index),X(:,index));
end
tmp2 = 2*a*kernel(ker,X,X(:,i_sv)); % 行向量
tmp3 = sum(sum(a'*a.*kernel(ker,X,X)));
R_square = tmp1-tmp2'+tmp3;
R_square = mean(R_square); % 超球半徑 R^2 (對所有支持向量求平均的結果)
nt = size(Xt,2); % 測試樣本數
tmp4 = zeros(nt,1); % 列向量
for i = 1:nt
tmp4(i) = kernel(ker,Xt(:,i),Xt(:,i));
end
tmp5 = 2*a*kernel(ker,X,Xt); % 行向量
Yd = sign(tmp4-tmp5'+tmp3-R_square);
case 'svr_epsilon',
tmp = a*kernel(ker,X,X(:,i_sv)); % 行向量
b = Y(i_sv)-tmp; % 符號不一樣,決策函數就不一樣,實際上是一回事!
%b = Y(i_sv)+tmp;
b = mean(b);
tmp = a*kernel(ker,X,Xt); % 符號不一樣,決策函數就不一樣,實際上是一回事!
%tmp = -a*kernel(ker,X,Xt);
Yd = (tmp+b);
case 'svr_nu',
%------------------------------------%
% 與'svr_epsilon' 情況相同
tmp = a*kernel(ker,X,X(:,i_sv)); % 行向量
b = Y(i_sv)-tmp; % 符號不一樣,決策函數就不一樣,實際上是一回事!
%b = Y(i_sv)+tmp;
b = mean(b);
tmp = a*kernel(ker,X,Xt); % 符號不一樣,決策函數就不一樣,實際上是一回事!
%tmp = -a*kernel(ker,X,Xt);
Yd = (tmp+b);
otherwise,
end
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