medfilt.m

来自「这是一个用于语音信号处理的工具箱」· M 代码 · 共 37 行

%FUNCTION: N-point median filter. y=medfilt(x,N)
function y=medfilt(x,N);
%% PURPOSE : select the medium point of each N consecutive sequence, N=3,5 or 7
%% input: x is the input and N is the order; if N is absent, default value is 3.
%% output: y is the median filter output.

if nargin<2
   N=3;
end

x=x(:)';
xlens=length(x);
N2=round((N-1)/2);

if xlens>(N-1)
   z=[zeros(1,N2) x zeros(1,N2)];

   % interpolate the beginning portion
   for i=1:N2
       z(i)=2*x(i)-x(i+1);
   end

   % interpolate the ending portion
   for i=1:N2
       z(i+xlens+N2)=2*x(xlens+1-i)-x(xlens-i);
   end

   % find the median point
   for i=(N2+1) : (xlens+N2)
       a=z(i-N2:i+N2); 
       y(i-N2)=median(a);
   end

else
   y=x;
end