How to use text file data as input to matlab code?

Hello, I need to use data in text file as a input to my matlab code. The data format in text file is as follows(each row has 4 columns: 1 for time, 2 for st. number, 3&4 are velocity components), Sample data:

Time St. DA DB

0 33 38.55 -10.87

2 33 37.35 -84.84

4 10 37.22 -62.29

6 43 37.39 -41.00

8 43 37.00 -19.75

I need to compare the time and st. number value with the values in my matlab code and pick 3&4 accordingly for further analysis. Any inputs are welcome.

Answer 1

[Stephen23]

Try using textscan. You should read the documentation and pay attention to the option HeaderLines, and how FormatSpec is defined.

It is also important to use fopen and fclose, something like this:

fid = fopen('mydata.txt','rt');
C = textscan(fid,'%s %s %f32 %d8 %u %f %f %s %f');
fclose(fid);

This might be interesting to read too:

http://matlab.wikia.com/wiki/FAQ#Can_I_read_a_text_file_with_a_certain_format.3F

[Shree]

Thank you!

[Stephen23]

Please do try it. If this solves your problem, you can click "Accept" for this answer. If the problem is unresolved, please explain what is not working.

[Shree]

Hey I am able to display rows bur not able to access exact value. I got 2 errors as follows.

1. fid = fopen('projectdata.txt','rt');

C = textscan(fid,'%n %n %n %n');

fclose(fid);

celldisp(C)

disp (C(1,1))

ans: [385x1 double]

But I need to access value at that location. How to get that value displayed?

2. fid = fopen('projectdata.txt','rt');

C = textscan(fid,'%n %n %n %n');

fclose(fid);

celldisp(C)

if C(1,1)==40

disp(C(1,2))

end

Error: Undefined function 'eq' for input arguments of type 'cell'.

[Stephen23]

So you might have something a bit like this:

fid = fopen('temp.txt','rt');
C = textscan(fid,'%f%f%f%f', 'HeaderLines',1);
fclose(fid);

Then you can access the data in C like this:

C{1} % The first column of data
...
C{4} % The fourth column of data

You could even merge all of the data into one numeric array, which would probably be easier to works with:

C = [C{:}];

[Shree]

How can I access a specific element? For example : 4th row and 2nd column

Is there a specific syntax to do that?

Because I am still not able to do operation like,

if C(1,1)==40

    disp(C(1,2))

end

This is because I am not able to access the number at that position and instead I am accessing the ans '[384x1 double]'

Is there any way to solve this?

[Stephen23]

If you try the code that I recommended at the bottom of my last comment

C = [C{:}];

then you will end up with a simple numeric matrix, and you can use the indexing as you show in your comment:

if C(1,1)==40
    ...
end

FYI: the function textscan returns a cell array. You can read about cell arrays and how to index into them here .

[Shree]

Thank you so much!

[Image Analyst]

If you want a table instead of a cell array, you can simply do

t = readtable(filename);

No need for fopen(), a format string, and fclose. I think it's a lot simpler but it requires release R2013b or later.