Value associate to a parameter in a text

So I have a text file similar to the following:

DELZZ 3301.23

KUTY 4.32 SERI -0.023

I want Matlab to read the file and return values associate to each parameter (DELZZ, KUTY,SERI,...) Any suggestion?

Answer 1

[Paolo]

 data = fileread('mytextfile.txt');
 val = regexp(data,'(?<=\s)(-?\d*\.?\d*)(?=\s|$)','match');

[Jack]

what does -?\d+\.?\d+ do?

[Paolo]

It's a regular expression which you can see in action live here.

• -? Matches a negative sign optionally.
• \d+ Matches digits.
• \. Matches a decimal point optionally.
• \d+ Matches more digits.

The output is:

val:

 {'3301.23'}    {'4.32'}    {'-0.023'}

If you need to perform numerical calculations you need to convert the character vectors to doubles:

 val = cellfun(@str2double,val);

Does that help you?

[Jack]

Thank you so much. And the last question, what if the name of parameters contained number, like

KUTY01 33.02

Fuzzy10 -0.923

or is it possible to ask Matlab: go ahead and find a value in front of a particular parameter? like find the value in front of "KUTY01" and it returns 33.02

[Paolo]

If you wanted the result for a specific case, i.e. KUTY01, you can use:

 (?<=KUTY01\s)-?\d+\.?\d+

The first part of the regular expression (?<=KUTY01\s) is a positive lookbehind.

As you can see here, it checks backwards to see if pattern KUTY01, followed by whitespace, is found. If it is, it matches the sequence of digits, decimal point and digits as explained in the previous comment. As you can see, only 33.02 is now matched.

If you found the answer useful consider accepting it/voting :)

[Jack]

it seems this command doesn't read a single digit number like

KUTY01 5

is that right?

[Paolo]

That's right, you will need to use the greedy * quantifier rather than the + quantifier. Since you need to match those values too, use:

(?<=KUTY01\s)-?\d*\.?\d*

I'll update my answer.

[Jack]

Thank u so much