jpanju.m

来自「在模式识别应用中」· M 代码 · 共 25 行

function y = Jpanju ( Xi )

global N1 N2 N c;
[ Nx , nx ] = size ( Xi );
mi = zeros ( c , nx );   %类内均值矢量
m = zeros ( 1 , nx );    %样本总体均值矢量
SW = zeros ( nx , nx );   %总的类内离差矩阵
SB = zeros ( nx , nx );   %总的类间离差矩阵
Ni = [ 0 , N1 , N2 ];

y = 0;
for k = 1 : c   %计算类内、总体均矢
    mi ( k , : ) = sum ( Xi ( sum ( Ni ( 1 : k ) ) + 1 : sum ( Ni ( 1 : ( k + 1 ) ) ) , : ) ) / Ni ( k + 1 );
    m = m + mi ( k , : ) * Ni ( k + 1 ) / N;
end

for k = 1 : c   %计算类间离差矩阵
    SB = SB + Ni ( k + 1 ) / N * ( mi ( k , : ) - m )' * ( mi ( k , : ) - m );
end

for k = 1 : N   %计算类内离差矩阵
    SW = SW + ( Xi ( k , : ) - m )' * ( Xi ( k , : ) - m ) / N;
end
y = trace ( SB ) / trace ( SW );%计算判据
return;