How to use for loop rather than nesting if loop

Question

Alex 2018-1-27

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/379295-how-to-use-for-loop-rather-than-nesting-if-loop

评论： Alex 2018-1-28

I want to use this code to subtract one value from each number in the histogram when all have been selected to find the new number with zero counts. This code worked (since there are two if loops with one nested) for the first two times 1 is subtracted from cdiff, but then returns the error 'Unbalanced or unexpected parenthesis or bracket.' : %check if Cdiff is empty:

if isempty(C_diff)
    fprintf('C_diff is empty (all numbers have drawn once) \n');
    cdiff_counts= counts - 1;%cdiff_data_vector = reshape(data,[9,numel(data)]); 
    C_diff = find(cdiff_counts==0);%return vector of values with 0
    fprintf('By subtracting 1 count for all numbers, the new C_diff is %d\n', C_diff);
    if isempty(C_diff)
        fprintf('C_diff is empty (all numbers have drawn once) \n');
        cdiff_counts= cdiff_counts - 1;%cdiff_data_vector = reshape(data,[9,numel(data)]); 
        C_diff = find(cdiff_counts==0);%return vector of values with 0
        fprintf('By subtracting 1 count for all numbers, the new C_diff is %d\n', C_diff);
    end
else
  fprintf('C_diff is %d\n', C_diff);%
end
Replacing the first 'if' with 'for' returns 'Unbalanced or unexpected parenthesis or bracket.'

How can I get this to occur until C_diff is no longer an empty array?

if isempty(C_diff)
      fprintf('C_diff is empty (all numbers have drawn once) \n');
      cdiff_counts= counts - 1;%cdiff_data_vector = reshape(data,[9,numel(data)]); 
      C_diff = find(cdiff_counts==0);%return vector of values with 0
      fprintf('By subtracting 1 count for all numbers, the new C_diff is %d\n', C_diff);
  else
    fprintf('C_diff is %d\n', C_diff);%
  end

Best regards,

Alex

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Jan 2018-1-27

There are no "if loops" in any programming language.

Alex 2018-1-27

ok, "if statement"?

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Answer 1

Jan 2018-1-27

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/379295-how-to-use-for-loop-rather-than-nesting-if-loop#answer_302045

编辑：Jan 2018-1-27

在 MATLAB Online 中打开

while isempty(C_diff)
  cdiff_counts = counts - 1;
  C_diff       = find(cdiff_counts == 0);
end

It looks like C_diff contains positive values initially, maybe only integers. Then this is more efficient:

minValue = min(counts);     % [EDITED]
C_diff   = find(C_diff = minValue);

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Jan 2018-1-27

I had a typo in the min() call. I assume, it is much cheaper. If you provide some meaningful inputs data and the wanted result, I could even test my suggestions.

Alex 2018-1-28

counts.mat

Thank you! I will keep that in mind for future questions. It is not necessary, but if you are interested, here is the "counts" data for numbers 1:1:49. The number 32 should be returned.

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