# Reading single value from text file

조회 수: 15(최근 30일)
Ted McG 2020년 9월 21일
답변: Ruger28 2020년 9월 21일
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
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Ted McG 2020년 9월 21일
yes

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### 채택된 답변

Ameer Hamza 2020년 9월 21일
편집: Ameer Hamza 2020년 9월 21일
Try this
peak_freq = regexp(str, 'Peak frequency \(Hz\) =[\s\t]*(\d*\.\d*)', 'tokens');
peak_freq = str2double(peak_freq{1}{1});
data.txt file is attached.

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### 추가 답변(1개)

Ruger28 2020년 9월 21일
One approach, which only works if these files dont change would be to read in and point to directly where the value is.
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:
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);

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