CODEWITHSUNDEEP
regexmatlab
Alex
Alex

Reputation: 1

Matlab: extract numbers including decimals and sign

I have a string in matlab that looks like this:

str =

    Z   1   -355.66338432    1
    Z   2      1.38339828     412    
    Z   3      9.00000000     412    
    Z   4    -10.27835665     312 22 - 1
    Z   5      3.00000000     612 2   2
    Z   6      6.53259554     612 2   2
    Z   7      5.00000000     812 33 - 2   
    Z   8      0.19040409     812 33 - 2   
    Z   9      2.00000000     812 3   3
    Z  10     -1.00534284     812 3   3
    Z  11      7.27727717     512 64 - 62  1

I want to extract the numbers in the third column but I can't seem to figure out the correct usage of regexp.

Upvotes: 0

Views: 1418

Answers (1)

Li-aung Yip
Li-aung Yip

Reputation: 12486

I don't have MATLAB handy, so I can't provide code. But generally: Step through the string one line at a time, and use the regex:

^\s*Z\s*\d+\s*(-?\d+\.\d+).*$

This will capture the number as the first capture group, \1. The regex expands as:

^                  Start of line
\s*Z\s*            First column - whitespace, literal `Z`, whitespace
\d+\s*a            Second column - integer number, whitespace
(-?\d+\.\d+)       Third column - a (possibly negative) decimal number.
.*                 Anything
$                  End of line

See it work on Regexr.

Alternately, use the tool that's actually meant for this job: textscan(). (Mathworks documentation.)

Upvotes: 1

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