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

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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.

Accepted Answer

Jeevan Kumar Bodaballa
Jeevan Kumar Bodaballa on 3 Nov 2020
I found soultion for this
I am attching sample file also for better understanding
fid = fopen('f20_CHEMISTRY.TXT','r');
data = textscan(fid,'%s');
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;
f20_pH = str2double(f20_pH);

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.
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.

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