在matlab中查找矩陣中具有相同值的最接近元素

Question

考慮以下矩陣：

0 3 0 1 1 4
1 3 5 6 7 0
2 5 6 2 6 1
4 4 2 1 5 1

當我指定一個元素的位置時，我想獲得具有相同值的最近元素的位置。例如，如果我選擇第3行第3列中的元素，即“ 6”，則我想獲得最接近的'6'的行和列的值，在這種情況下，它位於第2行的第4列。同樣，對於第4列的第1列的'1'，最接近的是第4行，列5第4，col 6行，它們中的任何一個都很好。我查詢了'bwdist'和'find'函數，但它們沒有給出正確的結果，有人可以幫我嗎？

編輯：

a1 = randi(10,10,5); 
disp(a1);
%// For an array of search numbers
search_array = a1(4,5);
disp(search_array);
%%// Find the linear index of the location
[~,ind] = min(abs(bsxfun(@minus,a1(:),search_array')));%//'

%%// Convert the linear index into row and column numbers
[x,y] = ind2sub(size(a1),ind) 

``min''函數在這里不起作用，因為存在所需元素的每個位置都將轉換為零，並且``min''逐行掃描矩陣並給出第一個零的位置。以下是這種情況：

 2     6    10     9     2
 6     6     7     5     3
 1     8     5     2     1
 8     1     9     5     5
 9     7     6     4     3
10     6     6     5     3
10     2     7     9     5
 6    10     4     5     2
 3     6     3     4     5
 2     5     6     4     8

即使第4行第5行中的“ 5”旁邊有一個“ 5”，第10行第2列中的“ 5”也會被選中。

Answer 1

假設A是輸入2D矩陣，這可能是一種方法-

%// Row and column indices of the "pivot"
row_id = 4;
col_id = 5;

%// Get the linear index from row and column indices
lin_idx = sub2ind(size(A),row_id,col_id)

%// Logical array with ones at places with same values
search_matches = false(size(A));
search_matches(A==A(lin_idx)) = 1;

%// Create a logical array with just a single 1 at the "pivot"
A_pivot = false(size(A));
A_pivot(lin_idx) = 1;

%// Use BWDIST to find out the distances from the pivot to all the places
%// in the 2D matrix. Set the pivot place and places with non-similar
%// values as Inf, so that later on MIN could be used to find the nearest
%// same values location
distmat = bwdist(A_pivot)
distmat(lin_idx) = Inf
distmat(~search_matches)=Inf

[~,min_lin_idx] = min(distmat(:))
[closest_row_idx,closest_col_idx] = ind2sub(size(A),min_lin_idx)

Answer 2

這種方法不需要任何工具箱。 如果不存在其他具有相同值的條目，則返回[] 。

A = [0 3 0 1 1 4
     1 3 5 6 7 0
     2 5 6 2 6 1
     4 4 2 1 5 1];                     %// data matrix
pos_row = 3;                           %// row of reference element
pos_col = 3;                           %// col of reference element

ref = A(pos_row,pos_col);              %// take note of value
A(pos_row,pos_col) = NaN;              %// remove it, to avoid finding it as closest
[ii, jj] = find(A==ref);               %// find all entries with the same value
A(pos_row,pos_col) = ref;              %// restore value
d = (ii-pos_row).^2+ (jj-pos_col).^2;  %// compute distances
[~, ind] = min(d);                     %// find arg min of distances
result_row = ii(ind);                  %// index with that to obtain result
result_col = jj(ind);