Walking Randomly

I had a query from a MATLAB user the other day and I thought I would share it with the world just in case it turned out to be useful to someone.  She had some data in a cell array that appeared as follows

data =

    '-0.000252594'
    '-0.788638'
    '-1.14636'
    '-1.15374'
    '-1.15474'

I’m not sure how she ended up with her data in this form but that’s not important here. What is important is that she couldn’t calculate with it in all the ways she was used to so what she asked was ‘how do I convert this cell array to a matrix?‘

It turns out that this is relatively easy to do since this particular cell array has a very simple form.  If you want to follow along then you can create an identical cell array as follows

data={'-0.000252594'; '-0.788638'; '-1.14636' ;'-1.15374' ;'-1.15474'}

data =

    '-0.000252594'
    '-0.788638'
    '-1.14636'
    '-1.15374'
    '-1.15474'

Let’s check that this really is a cell array using the iscell() function

iscell(data)

ans =
     1

Looks good so far. So, to convert this to a matrix all you need to do is

matdata=cellfun(@str2num,data)

matdata =
   -0.0003
   -0.7886
   -1.1464
   -1.1537
   -1.1547

the variable matdata is a standard MATLAB matrix and to prove it I’ll add 1 to all of the elements in the usual fashion

matdata+1

ans =
    0.9997
    0.2114
   -0.1464
   -0.1537
   -0.1547

That’s it! If only all queries were that simple