Question

Is there is easy command in MATLAB which prevents program from crashing when it reads characters?

I use xlsread to read a (20 400) matrix data , the first row and column get disregarded
as they have headers, so that:

data = xlsread ('C:\file.xls') 

results in data with a size of (19 399).

I have a problem, some cells have missing data and it’s written ‘missing’ and on some data sets i have headers reappear in middle.

Is there a way to skip these characters without the program crashing and me having to open the file in excel and deleting those fields?

Thanks

---

sorry for the late update. Here is the code i am using:

[a,patha]=uigetfile({'*.csv'},'Select the file' ,'c:\Data\2010'); 
file1=[patha a]; 

%# get a file ID 
fid = fopen(file1,'rt'); 
newf= textscan(fid, ['%s' repmat('%f',1,27)], 'HeaderLines', 1, 'Delimiter', ','); 
fclose(fid) ;

%//Make time a datenum of the first column
time = datenum(newf{1} );

%//Find the difference in minutes from each row
timeDiff = round(diff(datenum(time)*(24*60)));

%//the rest of the data
newf = cell2mat(newf(2:28));

the error i get is:

??? Error using ==> cat
CAT arguments dimensions are not consistent.

Error in ==> cell2mat at 81
            m{n} = cat(2,c{n,:});

Error in ==> testprogram at 31
pwr = cell2mat(newf(2:28));

it is due to the characters in my file i selected. it disappears when i manually delete them

Answer 1

Textscan fails if the string doesn’t match the expectation. The empty entries lead to problems when catenating – your array would have an uneven number of columns.

textscan('bla,5.4,missing,3,3,3.4','%s%f%f%f%f%f','Delimiter',',')

ans = 

    {1x1 cell}    [5.4000]    [0x1 double]    [0x1 double]    [0x1 double]    [0x1 double]

However, you can use’TreatAsEmpty’, to treat ‘missing’ as empty (i.e. they’re replaced by NaNs)

textscan('bla,5.4,missing,3,3,3.4','%s%f%f%f%f%f','Delimiter',',','TreatAsEmpty','missing')

ans = 

    {1x1 cell}    [5.4000]    [NaN]    [3]    [3]    [3.4000]

This allows you to run cell2mat without problems.