how to write an if statement for a matrix with some NaN elements?

2 次查看（过去 30 天）

Mnr 2015-5-5

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/215247-how-to-write-an-if-statement-for-a-matrix-with-some-nan-elements

编辑： Stephen23 2015-5-6

Hello all,

I have a matrix with some elements 0s or 1s and the rest are NaNs. I would like to write an if statement that ignores the NaN elements of the matrix. I have tried

if (a(:)==1 or a(:)==0) 
------------
end

however, I am getting an error. I would appreciate if somebody can help me please. Thanks.

7 个评论
显示 5更早的评论隐藏 5更早的评论

Stephen23 2015-5-6

编辑：Stephen23 2015-5-6

在 MATLAB Online 中打开

As Walter Roberson pointed out, it is very important to know that NaN is never equal to anything, not even itself:

>> NaN==NaN
ans =
      0

The only way to test for NaN is using isnan, (or by implication isinf and isfinite):

http://www.mathworks.com/help/matlab/ref/isnan.html

http://www.mathworks.com/matlabcentral/answers/59002-why-is-nan-not-equal-to-nan

http://matlab.wikia.com/wiki/FAQ#How_can_I_detect_NaN_values_in_a_matrix_or_vector.3F

http://www.mathworks.com/help/matlab/ref/nan.html

Walter Roberson 2015-5-6

~(A==A) is also a test for A being NaN.

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Walter Roberson 2015-5-5

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/215247-how-to-write-an-if-statement-for-a-matrix-with-some-nan-elements#answer_177968

在 MATLAB Online 中打开

nonnanlocs = ~isnan(a);
a(nonnanlocs) = SomeFunction(a(nonnanlocs));

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。

类别

MATLAB Language Fundamentals Data Types Numeric Types Logical

在 Help Center 和 File Exchange 中查找有关 Logical 的更多信息

Community Treasure Hunt

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

Start Hunting!

Translated by

how to write an if statement for a matrix with some NaN elements?

7 个评论
显示 5更早的评论隐藏 5更早的评论

回答（1 个）

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

另请参阅

类别

标签

Community Treasure Hunt

how to write an if statement for a matrix with some NaN elements?

7 个评论 显示 5更早的评论隐藏 5更早的评论

回答（1 个）

0 个评论 显示 -2更早的评论隐藏 -2更早的评论

另请参阅

类别

标签

Community Treasure Hunt

WeChat

7 个评论
显示 5更早的评论隐藏 5更早的评论

0 个评论
显示 -2更早的评论隐藏 -2更早的评论