Vectorizing a nested for loop which fills a dynamic programming table

2 ビュー (過去 30 日間)
Thomas Mathers
Thomas Mathers 2014 年 9 月 27 日
I was wondering if there was a way to vectorize the nested for loop in this function which is filling up the entries of the 2D dynamic programming table DP. I believe that at the very least the inner loop could be vectorized as each row only depends on the previous row. I'm not sure how to do it though. Note this function is called on large 2D arrays (images) so the nested for loop really doesn't cut it.
function [cols] = compute_seam(energy)
[r, c, ~] = size(energy);
cols = zeros(r);
DP = padarray(energy, [0, 1], Inf);
BP = zeros(r, c);
for i = 2 : r
for j = 1 : c
[x, l] = min([DP(i - 1, j), DP(i - 1, j + 1), DP(i - 1, j + 2)]);
DP(i, j + 1) = DP(i, j + 1) + x;
BP(i, j) = j + (l - 2);
end
end
[~, j] = min(DP(r, :));
j = j - 1;
for i = r : -1 : 1
cols(i) = j;
j = BP(i, j);
end
end

回答 (0 件)

カテゴリ

Help Center および File ExchangeLoops and Conditional Statements についてさらに検索

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by