MATLAB Answers

Reading single value from text file

15 views (last 30 days)
Ted McG
Ted McG on 21 Sep 2020
Answered: Ruger28 on 21 Sep 2020
Hello all,
I am reading in text files of the following format and would like to extract just the Peak frequency value (6.8 below) and put it into an array. What is the easiest way to do this? Thanks, fairly new to MATLAB.
Vibration Test
9/16/2020 2:12:25 PM
Sample Rate (Hz) = 2000.00
Peak frequency (Hz) = 6.8 Resolution (Hz) = 0.2
  2 Comments

Sign in to comment.

Accepted Answer

Ameer Hamza
Ameer Hamza on 21 Sep 2020
Edited: Ameer Hamza on 21 Sep 2020
Try this
str = fileread('data.txt');
peak_freq = regexp(str, 'Peak frequency \(Hz\) =[\s\t]*(\d*\.\d*)', 'tokens');
peak_freq = str2double(peak_freq{1}{1});
data.txt file is attached.

More Answers (1)

Ruger28
Ruger28 on 21 Sep 2020
One approach, which only works if these files dont change would be to read in and point to directly where the value is.
fname = 'C:\Users\<username>\Desktop\SampleFile.txt';
FID = fopen(fname);
x = textscan(FID,'%s');
fclose(FID);
freqVal = str2double(x{1,1}{15,1});
This looks directly at the location of the freq, that is if this file format never changes. Another method would be to use fgetl to extract each line, and search for your key terms, such as:
fname = 'C:\Users\<username>\Desktop\SampleFile.txt';
FID = fopen(fname);
loopcnt = 1;
while loopcnt
temp = fgetl(FID);
if any(strfind(temp,'Peak frequency (Hz) ='))
startI = regexp(temp,'=','once');
stopI = regexp(temp,'Resolution','once');
Freq = str2double(strtrim(temp(startI+1:stopI-1)));
break
end
end
fclose(FID);

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by