For loop isn't working, unsure as to why

Question

Robert 2016-4-19

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/279720-for-loop-isn-t-working-unsure-as-to-why

编辑： James Tursa 2016-4-19

In the following code, 'forrest', 'shrub', 'sav', 'grass' and 'agri' have all been initialized at 35*43 matrices of NaNs.

'lut' and 'D10weight' are also 35,43 matrices. The idea is that each of 'forrest', 'shrub', 'sav', 'grass' and 'agri' get values from 'D10weight' where 'lut' equals a certain number. However they all remain as NaNs and I am unsure why.

for i = 1:35;
    j = 1:43;
      if lut(i,j) == 1
          forrest(i,j) = D10weight(i,j);
      end
      if lut(i,j) == 2
          shrub(i,j) = D10weight(i,j);
      end
      if lut(i,j) == 3
          sav(i,j) = D10weight(i,j);
      end
      if lut(i,j) == 4
          grass(i,j) = D10weight(i,j);
      end
      if lut(i,j) == 5
          agri(i,j) = D10weight(i,j);
      end
  end

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

James Tursa 2016-4-19

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/279720-for-loop-isn-t-working-unsure-as-to-why#answer_218473

编辑：James Tursa 2016-4-19

在 MATLAB Online 中打开

I think you meant for this to be a double for loop. As coded, you only have one for loop and j is a vector. E.g., is this what you meant?

for i = 1:35;
   for j = 1:43;
      if lut(i,j) == 1
          forrest(i,j) = D10weight(i,j);
      end
      if lut(i,j) == 2
          shrub(i,j) = D10weight(i,j);
      end
      if lut(i,j) == 3
          sav(i,j) = D10weight(i,j);
      end
      if lut(i,j) == 4
          grass(i,j) = D10weight(i,j);
      end
      if lut(i,j) == 5
          agri(i,j) = D10weight(i,j);
      end
    end
 end

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Robert 2016-4-19

Thanks, looks like that was the problem all along, it's obvious now that you've pointed it out. Thanks again

请先登录，再进行评论。

Answer 2

Image Analyst 2016-4-19

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/279720-for-loop-isn-t-working-unsure-as-to-why#answer_218469

Here is a way 100% guaranteed to help you solve it: http://blogs.mathworks.com/videos/2012/07/03/debugging-in-matlab/

Have you tried actually stepping through line by line and checking the value of lut(i,j) and seeing why your "if" statements never get true and so never assigns anything?