MATLAB Answers

How to search and extract specific string and data and write into new variable from file ?

5 views (last 30 days)
I have data containes lot of different values like this
BULK VARIABLES NW= 0.197E+10 QW= 0.302E-03 QWA= 0.931E-07
QSO2= 0.000E+00 QO3= 0.000E+00 QH2O2= 0.000E+00 QCO2= 0.000E+00 QNH3= 0.000E+00 QSO4 = 0.000E+00 QHMO3= 0.000E+00 pH= 0.594E+01 CONDUCT= 0.239E-01
And I would like to search pH= ****** at every line and extract from the file and write into a new variable (nx1).
you can find sample file in attached file.

  0 Comments

Sign in to comment.

Accepted Answer

Jeevan Kumar Bodaballa
Jeevan Kumar Bodaballa on 3 Nov 2020 at 11:17
I found soultion for this
I am attching sample file also for better understanding
clear
fid = fopen('f20_CHEMISTRY.TXT','r');
data = textscan(fid,'%s');
fclose(fid);
Str = string(data{:});
% this loop for pH values
%check the numbers(33 to 1484 in my case)
% In str array from where you want to make reshape
% below loop will extract the value and write new array
y = 1;
for j = 33:1484:length(Str)
f20_pH(y) = Str(j,:);
y = y+1;
end
f20_pH = str2double(f20_pH);
save('f20_pH_con.mat','f20_pH')

  0 Comments

Sign in to comment.

More Answers (1)

Anmol Dhiman
Anmol Dhiman on 10 Sep 2020
Hi Jeevan,
You can follow the below approach
fid = fopen('pH.txt'); % Open the file
line_ex = fgetl(fid); % read a line
newStr = split(line_ex); % split the line based on delimeter space.IT gives a cell array
indexOfPH = find(contains(newStr, 'pH=')); % search if any of the elements is mathing with 'pH='
newVariable = newStr{indexOfPH+1} ; % store the value in a variable
% To read next line
line_ex = fgetl(fid);
You need to write in a loop.
Regards,
Anmol Dmiman

  1 Comment

Jeevan Kumar Bodaballa
Jeevan Kumar Bodaballa on 26 Sep 2020
Sorry for late answer
I follow the script you wrote but I am getting error at 5th line
'Unable to perform assignment with 0 elements on the right-hand side.'
Also please suggest the loop as well.

Sign in to comment.

Community Treasure Hunt

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

Start Hunting!