[英]How do I get rid of NaNs in MATLAB?
I have files which have many empty cells which appear as NaNs when I use cell2mat
, but the problem is when I need to get the average values I cannot work with this as it shows error with NaN. 当我使用cell2mat
时,我有许多空单元格的文件显示为NaN,但问题是当我需要获得平均值时,我无法使用它,因为它显示NaN的错误。 In excel it overlooks NaN values, so how do I do the same in MATLAB? 在excel中它忽略了NaN值,那么我如何在MATLAB中做同样的事情呢?
In addition, I am writing a file using xlswrite
: 另外,我正在使用xlswrite
编写一个文件:
xlswrite('test.xls',M);
I have data in all rows except 1. How do I write: 我的所有行都有数据,除了1.我怎么写:
M(1,:) = ('time', 'count', 'length', 'width')
In other words, I want M(1,1)='time'
, M(1,2)='count'
, and so on. 换句话说,我想要M(1,1)='time'
, M(1,2)='count'
,依此类推。 I have data from M(2,1)
to M(10,20)
. 我有从M(2,1)
到M(10,20)
。 How can I do this? 我怎样才能做到这一点?
As AP correctly points out , you can use the function isfinite
to find and keep only finite values in your matrix. 正如AP正确指出的那样 ,您可以使用函数isfinite
来查找并保留矩阵中的有限值。 You can also use the function isnan
. 您还可以使用isnan
函数。 However, removing values from your matrix can have the unintended consequence of reshaping your matrix into a row or column vector: 但是,从矩阵中删除值可能会导致将矩阵重新整形为行或列向量的意外后果:
>> mat = [1 2 3; 4 NaN 6; 7 8 9] % A sample 3-by-3 matrix
mat =
1 2 3
4 NaN 6
7 8 9
>> mat = mat(~isnan(mat)) % Removing the NaN gives you an 8-by-1 vector
mat =
1
4
7
2
8
3
6
9
Another alternative is to use some functions from the Statistics Toolbox (if you have access to it) that are designed to deal with matrices containing NaN values . 另一种方法是使用统计工具箱中的一些函数(如果您有权访问它们),这些函数用于处理包含NaN值的矩阵 。 Since you mention taking averages, you may want to check out nanmean
: 既然你提到平均值,你可能想看看nanmean
:
>> mat = [1 2 3; 4 NaN 6; 7 8 9];
>> nanmean(mat)
ans =
4 5 6 % The column means computed by ignoring NaN values
EDIT: To answer your additional question on the use of xlswrite
, this sample code should illustrate one way you can write your data: 编辑:要回答有关使用xlswrite
其他问题,此示例代码应说明您可以编写数据的一种方法:
C = {'time','count','length','width'}; % A cell array of strings
M = rand(10,20); % A 10-by-20 array of random values
xlswrite('test.xls',C); % Writes C to cells A1 through D1
xlswrite('test.xls',M,'A2:T11'); % Writes M to cells A2 through T11
Use ' isfinite ' function to get rid of all NaN and infinities 使用'isfinite'函数来消除所有NaN和无穷大
A=A(isfinite(A)) A = A(ISFINITE(A))
%create the cell array containing the column headers columnHeader = {'Column 1', 'Column 2', 'Column 3', 'Column 4', 'Column 5',' '}; %创建包含列标题的单元格数组columnHeader = {'Column 1','Column 2','Column 3','Column 4','Column 5','}};
%write the column headers first xlswrite('myFile1.xls', columnHeader ); %首先写下列标题xlswrite('myFile1.xls',columnHeader);
% write the data directly underneath the column headers xlswrite('newFile.xls',M,'Sheet1','A2'); %直接在列标题xlswrite('newFile.xls',M,'Sheet1','A2')下面写入数据;
Statistics Toolbox has several statistical functions to deal with NaN values. Statistics Toolbox有几个统计函数来处理NaN值。 See nanmean, nanmedian, nanstd, nanmin, nanmax, etc. 参见nanmean,nanmedian,nanstd,nanmin,nanmax等。
您可以将NaN设置为任意数字,如下所示:
mat(isnan(mat))=7 // my lucky number of choice.
May be too late, but... 可能为时已晚,但......
x = [1 2 3; 4 inf 6; 7 -inf NaN];
x(find(x == inf)) = 0; //for inf
x(find(x == -inf)) = 0; //for -inf
x(find(isnan(x))) = 0; //for NaN
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