矩陣加跳過NaN值

Question

我想在矩陣上做元素明智的加法，同時跳過NaN值。 MATLAB和Octave有nansum，但它在矩陣中進行列式加法。

令：

a = NaN * zeros(3) 
b = ones(3) 

我想：

c = nan+(a, b) 

和

c = b 

和：

d = nan+(a,a) 

和

d = a 

Answer 1

您仍然可以使用nansum，如果您的鏈狀正d陣列沿第n + 1維。

對於2D

% commands de-nested for readability. You can do this with a single line, of course 
tmp = cat(3,a,b); 
c = nansum(tmp,3); 

一般情況下

function out = nansumByElement(A,B) 
%NANSUMBYELEMENT performs an element-wise nansum on the n-D arrays A and B 
% A and B have to have the same size 

% test input 
if nargin < 2 || isempty(A) || isempty(B) || ndims(A)~=ndims(B) || ~all(size(A)==size(B)) 
error('please pass two non-empty arrays of the same size to nansumByElement') 
end 

% calculate output 

nd = ndims(A); % get number of dimensions 
% catenate and sum along n+1st dimension 
out = nansum(cat(nd+1,A,B),nd+1); 

Answer 2

a_fixed = a; 
a_fixed(isnan(a)) = 0; 
b_fixed = b; 
b_fixed(isnan(b)) = 0; 
c = a_fixed.+b_fixed;