How can I avoid error in mnrfit line 164?

Question

Shiladitya Sen 2013-7-19

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I am getting an error message when I use the mnrfit function on a matrix X and Y like this:

X =

     1   NaN     2
   NaN     3   NaN
   NaN   NaN     4
     6   NaN   NaN
     5   NaN   NaN

Y =

    -1
     1
    -1
     1
    -1
 b=mnrfit(X,Y+2);
Error using mnrfit (line 164)
X and Y must contain at least one valid observation.

I cannot understand why I'm running into such an error...please advise...

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Answer 1

Wayne King 2013-7-19

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编辑：Wayne King 2013-7-19

The problem is that you have NaNs in every single row of your X matrix.

As the documentation states:

"mnrfit treats NaNs in X and Y as missing data, and removes the corresponding observations."

Every row in your X matrix is an observation on P predictor variables.

Since you have at least one NaN for every observation, all the observations are removed.

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Shiladitya Sen 2013-7-19

In that case, how should I perform logistic regression on a sparse dataset like this?

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Answer 2

Thomas 2013-7-19

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在 MATLAB Online 中打开

I'm assuming mnrfit does not like 'NaN' values as its input.

works fine with

 x =
          0.14          0.66          0.76
          0.42          0.04          0.74
          0.92          0.85          0.39
          0.79          0.93          0.66
          0.96          0.68          0.17
 y =
         -1.00
          1.00
         -1.00
          1.00
         -1.00
 b=mnrfit(x,y+2)
 b =
         95.33         47.37
        -58.97        -31.76
         15.27          6.52
       -112.15        -62.24