Why does str2double command return NaN? What type of array should I convert into for running fitlm command??

Question

Seraphic 2023-5-31

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1976434-why-does-str2double-command-return-nan-what-type-of-array-should-i-convert-into-for-running-fitlm-c

评论： Seraphic 2023-6-3

采纳的回答： Star Strider

在 MATLAB Online 中打开

Hi all,

This issue is holding me over two hours so I want to ask how to fix it.

My dataset is a 48X1 cell array, and want to run comman fitlm to derive AR(1) process - yes, it is time series data.

x =
  48×1 cell array
    {[  7.9614]}
    {[  6.6333]}
    {[  6.5029]}
    {[  5.9425]}
    {[  1.8100]}
    {[ -0.4337]}
    {[ -2.9584]}
    {[ -1.9444]}
    {[ -0.9811]}
    {[ -1.2110]}
    {[  0.0166]}
    {[ -0.7115]}
    {[ -1.4040]}
    {[  1.0919]}
    {[  1.8558]}
    {[ 11.2266]}
    {[  0.3792]}
    {[ -1.9763]}
    {[ -4.0722]}
    {[-16.7206]}
    {[ -6.4143]}
    {[ -5.3453]}
    {[ -2.5355]}
    {[  1.8669]}
    {[  3.4383]}
    {[  5.9412]}
    {[  5.4722]}
    {[ 11.5480]}
    {[  6.3237]}
    {[  5.7294]}
    {[  4.7529]}
    {[  4.0313]}
    {[  3.4431]}
    {[  1.5301]}
    {[ -0.4894]}
    {[ -7.7308]}
    {[ -3.1757]}
    {[ -8.3770]}
    {[ -1.9913]}
    {[  0.7572]}
    {[  7.9531]}
    {[ 16.1144]}
    {[ 14.1777]}
    {[ 13.6904]}
    {[  9.4649]}
    {[  9.7910]}
    {[  5.4224]}
    {[  1.8821]}

I want to conert the dataset x to run a regression but don't know which type of data I should convert to. In the first place, I tried str2double but it returned only 48 NaNs. I tried to cell2mat but it didn't work either. What command should I use for running fitlm?

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Answer 1

Star Strider 2023-5-31

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1976434-why-does-str2double-command-return-nan-what-type-of-array-should-i-convert-into-for-running-fitlm-c#answer_1247974

在 MATLAB Online 中打开

Of course str2double returned NaN for all of them because none of them are strings or character vectors.

I suspect there are concatenation brackets missing. That aside, the easiest way to do what you want is to use cell2mat —

x = [{[  7.9614]}
    {[  6.6333]}
    {[  6.5029]}
    {[  5.9425]}
    {[  1.8100]}
    {[ -0.4337]}
    {[ -2.9584]}
    {[ -1.9444]}
    {[ -0.9811]}
    {[ -1.2110]}
    {[  0.0166]}
    {[ -0.7115]}
    {[ -1.4040]}
    {[  1.0919]}
    {[  1.8558]}
    {[ 11.2266]}
    {[  0.3792]}
    {[ -1.9763]}
    {[ -4.0722]}
    {[-16.7206]}
    {[ -6.4143]}
    {[ -5.3453]}
    {[ -2.5355]}
    {[  1.8669]}
    {[  3.4383]}
    {[  5.9412]}
    {[  5.4722]}
    {[ 11.5480]}
    {[  6.3237]}
    {[  5.7294]}
    {[  4.7529]}
    {[  4.0313]}
    {[  3.4431]}
    {[  1.5301]}
    {[ -0.4894]}
    {[ -7.7308]}
    {[ -3.1757]}
    {[ -8.3770]}
    {[ -1.9913]}
    {[  0.7572]}
    {[  7.9531]}
    {[ 16.1144]}
    {[ 14.1777]}
    {[ 13.6904]}
    {[  9.4649]}
    {[  9.7910]}
    {[  5.4224]}
    {[  1.8821]}]
x = 48×1 cell array
    {[ 7.9614]}
    {[ 6.6333]}
    {[ 6.5029]}
    {[ 5.9425]}
    {[ 1.8100]}
    {[-0.4337]}
    {[-2.9584]}
    {[-1.9444]}
    {[-0.9811]}
    {[-1.2110]}
    {[ 0.0166]}
    {[-0.7115]}
    {[-1.4040]}
    {[ 1.0919]}
    {[ 1.8558]}
    {[11.2266]}
xv = cell2mat(x)
xv = 48×1
    7.9614
    6.6333
    6.5029
    5.9425
    1.8100
   -0.4337
   -2.9584
   -1.9444
   -0.9811
   -1.2110
xv = [x{:}].'                           % Alternative Approach
xv = 48×1
    7.9614
    6.6333
    6.5029
    5.9425
    1.8100
   -0.4337
   -2.9584
   -1.9444
   -0.9811
   -1.2110