Is MATLAB is automatically concatenating data from a text file?

I have an input line of text that looks like this:

Band ID: 0 AD ID: 43 Scan ID: 0 LRT/HRT: 0 Valid Flag: 0

Note that the text file has a tab after each number except the last one.

I’ m using the following regexp command to split the string;

Data = regexp(LineText,’ +’,’split’);

Actual output:

Band ID: 0AD ID: 43Scan ID: 0LRT/HRT: 0Valid Flag: 0

Expected output:

Band ID: 0 AD ID: 43 Scan ID: 0 LRT/HRT: 0 Valid Flag: 0

Where all numerical values are in there own cell. Also note that if the tabs that occur after each number are only spacs, I get the required result.

I don’t believe I’ve seen the regexp function behave in this manner. Is this a case where regexp is choking on the tabs in the text file? Or is my regexp too generic?

Answer 1

[Cedric]

What are you trying to achieve, extract the numbers? The space in the pattern ' +' won't match tabs actually, but '\s+' would (match spaces, tabs, any "white space"). If your goal were to extract numbers, you could go for

 >> match = regexp(LineText,'\d+','match') ;
 >> num = str2double(match)
 num =
     0    43     0     0     0

If you had a whole file with this structure, you could process it in one shot instead of line by line (for the example, I repeated several times this LineText that you provided and just incremented the AD value)..

 >> buffer = fileread('brad.txt') ;
 >> num = str2double(regexp(buffer,'\d+','match')) ;
 >> num = reshape(num, 5, []).'
 num =
     0    43     0     0     0
     0    44     0     0     0
     0    45     0     0     0
     0    46     0     0     0

and you could use more elaborate patterns if numbers were not integers, e.g. '[\d\.-]+' for matching positive and negative floating points as well.

[Brad]

Cedric, thank you again. Not only does this work like a champ, it also shows I got a long ways to go with regular expressions.

[Cedric]

You're welcome Brad. I think that we all have still have always something to learn about these regexp to be honest ;-) I could not recommend enough the official doc actually if you want to learn; it is one of the best documents that I have seen about them, in the sens that it is quite concise, yet very explicit with examples and it covers a lot of material quite well. You can find it there:

http://www.mathworks.com/help/pdf_doc/allpdf.html

Take the document called Programming Fundamentals in the MATLAB section, on pages 2-26 to 2-85.

Answer 2

[David Sanchez]

Is this what you want?

s='Band ID: 0 AD ID: 43 Scan ID: 0 LRT/HRT: 0 Valid Flag: 0';

data= regexp(s,'\t','split')

you will end up with an cell containing the data string.