MATLAB Answers

read a text file, use strcmpi function

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Mohammed Hamed
Mohammed Hamed on 1 Jan 2019
Commented: Mohammed Hamed on 8 Jan 2019
i would like the matlab to read a text file which are like :
i used strcmpi fuction but it didn't work.
so i wwould like some help so i can read junctions, reservoirs, pipes. each one alone
toggle = true;
while toggle== true
aline = fgetl(fid);
% test whether the line begins with "Start", and flip toggle
if strcmpi(aline(1:5),'[junc')
toggle = false;
end
end
Capture.PNG

  3 Comments

vik
vik on 1 Jan 2019
It might be easier to answer your question if you attach the original textfile (or parts of it) instead of an image.
One way of importing such files is to use textscan and use newline-char as delimiter:
fileID = fopen(filename,'r','ieee-le','windows-1258'); % open file
data_rows = textscan(fileID,'%s','Delimiter','\n'); % read whole file
fclose(fileID); % close file
n_rows = size(data_rows{1},1) % Determine number of rows
data_rows is a cell array containing each line now. You can then loop through the lines by using for:
for nf_row = 1:n_rows
row_current = ... % Get current row and split with Tab as delimiter:
textscan(data_rows{1}{nf_row},'%s','Delimiter','\t');
% More code to analyze file goes here, read and compare
% the [THING]-field and determine what to do next.
end
This needs more coding to work but the general thing worked for me so far quite nice.
Rik
Rik on 1 Jan 2019
@vik, you can move this comment to the answer section. I would only add that the code Mohammed posted probably failed on an empty line, due to a length check missing.
@Mohammed, you can either use the code vik suggested, or use the contains function instead of comparing the first few chars. You could also keep your current code and add in a test for size:
if numel(aline>=5) && strcmpi(aline(1:5),'[junc')

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Accepted Answer

Jan
Jan on 2 Jan 2019
toggle = true;
while toggle % not required, because it is a logical already: == true
aline = fgetl(fid);
toggle = ~strncmpi(aline, '[junc', 5)
end
strncmpi works also with lines, which are shorter than 5 characters. Instead of the if clause, you can set the value of toggle directly.

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More Answers (1)

vik
vik on 2 Jan 2019
Edited: vik on 3 Jan 2019
A quick and dirty code without preallocation to read the attached .txt-file would be like this:
filename='example_437840.txt';
fileID = fopen(filename,'r','ieee-le','UTF-8'); % open file
data_rows = textscan(fileID,'%s','Delimiter','\n'); % read whole file
fclose(fileID); % close file
n_rows = size(data_rows{1,1},1); % Determine number of rows
% Init some counters
idx_jun = uint32(0);
idx_res = uint32(0);
idx_pip = uint32(0);
for nf_row = 3:n_rows % Start at Line 3
if ~isempty(data_rows{1,1}{nf_row,1}) % Check if not empty
row_current = ... % Get current row and split with Tab as delimiter:
textscan(data_rows{1,1}{nf_row,1},'%s','Delimiter','\t');
% Determine what to do if line starts with a new heading
if strcmp(row_current{1,1}{1,1}(1,1),'[') % If line starts with [
% Get the String between those two bracktes:
m = row_current{1,1}{1,1}(2:end-1); % and set the switch-thing
elseif ~strcmp(row_current{1,1}{1,1}(1,1),';') % also skip ;-Lines
% In all other cases, read lines depending on what to do:
switch(m)
case 'JUNCTIONS'
idx_jun = idx_jun + 1; % Increase counter
% Get Data from the current row split at tabs:
jun_id(idx_jun) = str2double(row_current{1,1}{1,1});
jun_elev(idx_jun) = str2double(row_current{1,1}{2,1});
jun_dem(idx_jun) = str2double(row_current{1,1}{3,1});
case 'PIPES'
idx_pip = idx_pip + 1;
% Get Data from the current row split at tabs:
pip_id(idx_pip) = str2double(row_current{1,1}{1,1});
pip_node1(idx_pip) = str2double(row_current{1,1}{2,1});
pip_node2(idx_pip) = str2double(row_current{1,1}{3,1});
pip_length(idx_pip) = str2double(row_current{1,1}{4,1});
case 'RESERVOIRS'
idx_res = idx_res + 1;
% Same as above and more cases maybe
end % switch(m)
end % if strcmp(row_current{1,1}{1,1}(1,1),'[')
end %if ~isempty(data_rows{1,1}{nf_row,1})
end %for nf_row = 3:n_rows
It worked so far but may need some more optimization in case the file differs. Maybe there is a more nice way to extract the string between those two square brackets.

  1 Comment

Mohammed Hamed
Mohammed Hamed on 8 Jan 2019
Thank you indead for your support, but the code you provide only works in a specific file.
The number of pipes, junction, reservoirs are changed in each file

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