MATLAB: Using regexp to Search Large Text File for Wanted Data

dataregexp

Hello all! I am attempting to utilize regexp to extract wanted items from text files. Attached below is a sample text file. I wish to extract the start date, EL HGT and Northing (Y)/Easting (X) for UTM (Zone 15). I will eventually have a series of 365 of these text files compressed into one file. Is regexp the best method and how would it be coded? Thanks.

Best Answer

is regexp the best method?
For EL HGT, probably. For your Northing/Easting for UTM(Zone 15), no because extracting that value involve crossreferencing rows and columns. For that you would have to parse the whole file, and you would have to write your own parser as none of matlab built-in parsers (textscan, etc.) can parse a file that complex as is.
However, if UTM(Zone 15) is always the first column of number for Northing/Easting, then yes you could use a regexp:
filecontent = fileread('sample.txt');
el_hgt_full = regexp(filecontent, '(?<=EL HGT:\s*)[^\n\r]*', 'match', 'once');
el_hgt = str2double(regexp(el_hgt_full, '[+-]?\d+(\.\d+)?', 'match'));
northing = str2double(regexp(filecontent, '(?<=Northing \(Y\) \[meters\]\s*)[+-]?\d+(\.\d+)?', 'match', 'once'));
easting = str2double(regexp(filecontent, '(?<=Easting \(X\)  \[meters\]\s*)[+-]?\d+(\.\d+)?', 'match', 'once'));
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