if statement deleting cells

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cormac spillane 2015-4-25

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评论： cormac spillane 2015-4-25

I want to use the if function to delete every row in a matrix D that has a cell with -99.99 , there are a total of 582 rows and 2 colmuns if that helps. Any assistance would be greatly appreciated.

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Stephen23 2015-4-25

In MATLAB a cell refers to an element of a cell array, whereas for numeric and characters arrays the individual vlaues are called the elements.

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Answer 1

Stephen23 2015-4-25

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编辑：Stephen23 2015-4-25

在 MATLAB Online 中打开

There is one very important point to consider, and that is that checking for equivalence of floating point values is not recommended:

http://www.mathworks.com/matlabcentral/answers/57444-faq-why-is-0-3-0-2-0-1-not-equal-to-zero

http://www.mathworks.com/matlabcentral/answers/69-why-does-1-2-3-1-3-not-equal-zero

Instead of checking that the value is equal to -99.99 you should check that the values is inside a range of values, or equivalently use a tolerance values in a comparison:

>> tol = 0.01;
>> val = -99.99;
>> D = [1,2,3;4,5,-99.99;6,7,8;9,-99.99,0] % fake data
D =
          1            2            3
          4            5       -99.99
          6            7            8
          9       -99.99            0
>> D(any(abs(D-val)<=tol,2),:) = []
D =
   1     2     3
   6     7     8

This solution uses vectorized code and logical indexing, which will be faster than solving this in a loop. It also extends nicely as the arrays get larger, unlike a loop.