how to obtain the number of lines starting with a given string from an external text file and save the numeric value of variables of those lines

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Hugo 2020-9-28

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评论： Hugo 2020-9-29

采纳的回答： Sudheer Bhimireddy

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Hello,

I have an external text file. A part of the text file (example) is shown below:

/AA
/BB
/CC
DRL=1
DRL=2
DRL=4
/XX
/YY
/ZZ

How can I :

-Obtain the number of lines starting with "DRL" and save it to the variable pnumber. In this case pnumber=3

-save the value of those variables in the vector A, in my example A =[1;2;4]

I thank you in advance for any help,

Best regards,

Hugo

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采纳的回答

Sudheer Bhimireddy 2020-9-28

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Another approach:

data      = readtable('test.txt');    % test.txt contains the given text
drl_count = sum(strcmp(data.Var1,'DRL'));
drl_value = data.Var2(strcmp(data.Var1,'DRL'));
>> drl_count =
     3
drl_value =
     1
     2
     4

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Sudheer Bhimireddy 2020-9-29

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I would say first, try fopen with the .lgw and if it didn't work then convert to txt file.

Try this:

file_ID = fopen('data2.txt','rt'); % Opens file in text mode
% Number of lines to read
nLine_limit = 8; 
% Pre-allocate
data{nLine_limit,1} = 0;
nLine = 1;
% Read first few lines based on nLine_limit
while nLine <= nLine_limit
    data{nLine,1} = fgetl(file_ID); % Read the entire line
    nLine = nLine + 1;
end
fclose(file_ID);
% Filter out the lines with DRL in them and get their indices
drl_Line_Mask = ~cellfun(@isempty, regexp(data,'DRL','match'));
% Seperate all DRL lines
drl_data  = data(drl_Line_Mask);
% Split the cells based on '='
drl_split = regexp(drl_data,'=','split');
% Count number of lines with DRL 
drl_count = numel(drl_split);
% Pre-allocate
drl_value(drl_count,1) = nan;
for i=1:size(drl_split)
    drl_value(i,:)  = str2double(drl_split{i,1}{1,2});
end

Hugo 2020-9-29

It works perfectly!! Thank you very much!!!

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更多回答（1 个）

Ameer Hamza 2020-9-28

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编辑：Ameer Hamza 2020-9-28

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data.txt

Try this

f = fileread('data.txt');
lines = textscan(f, '%s');
lines = lines{1};
idx = cellfun(@(x) x(1)=='/', lines);
lines(idx) = [];
pnumber = numel(lines);
A = cellfun(@(x) sscanf(x, 'DRL=%d'), lines);