Use of cellfun to obtain the 2 element ONLY

Hi!

So I have a dataset with all the elements/answers being: 'A1 A2 A3 A4'. I need to transform those elements into '1, 2, 3,4'. Basically I just need to get rid of the 'A'. I have been trying this > Mydata=cellfun(@(x)x(2),Mydata); Im trying to extract the second element only (1,2,3,4) for the whole dataset but I get the followign error:

Index exceeds the number of array elements (0).

Error in @(x)x(2)

The format is 'cell' (not table). I then need to apply a fuction to substract 1 to each element, so 1=0, 2=1, 3=2 and 4=3. If anyone could help me i would really appreciate it! I'm obviously very new to matlab.

Many thanks!

[Walter Roberson]

At least one of the elements of Mydata is an empty cell.

[Natalia Lopez]

Thank you for your answer, yes I do have some missing data points. is there a way I can go around this? maybe just substituing the missing points for Nan or '.'?

Answer 1

[Bruno Luong]

>> c={'A1' 'A2' 'A3' 'A4' ''}

c =

  1×5 cell array

    {'A1'}    {'A2'}    {'A3'}    {'A4'}    {0×0 char}

This throw an error

Mydata=cellfun(@(x)x(2),c)
Index exceeds the number of array elements (0).

Error in @(x)x(2)
 

This works but returns -16 for empty cell.

a=char(c);
num=a(:,2)-'0'

num =

     1
     2
     3
     4
   -16
   

You can replace with NaN

num(num<0)=NaN

num =

     1
     2
     3
     4
   NaN

[Natalia Lopez]

Thanks for your answer, I did try it and it now I got the error:

Index in position 2 exceeds array bounds (must not exceed 1).

%Importfile(Mydata)

load(Mydata.mat');

Mydata = xData(:,i); %coded as A1, A2, A3, A4, -> change to 1 2 3 4

Mydata = table2array(data2); % convert to cell array

ids= cellfun(@(x) x(2),data2); % to each cell, apply the inline function that takes the second element

[Bruno Luong]

Try my second method

Answer 2

[Walter Roberson]

cellfun(@(S) sscanf(S,'%*c%d'), c, 'uniform', 0)