Reading textfile using fopen and textscan

Question

Sam 2020-10-6

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/606116-reading-textfile-using-fopen-and-textscan

编辑： Stephen23 2020-10-6

Hello,

I've got a textfile 'test_file.txt' which you can find in attachment.

At the bottom of this textfile, you can see ' [Channel Data] '. I would like to extract all headers beneath ' [Channel Data] ' except the last 2. So I would like to extract the headers ' S.No., Data&Time, hf2, hf3, hf4, hf10, hf6, tc18, tc3, tc5, tc7, tc9, tc11, tc12, tc13, tc15, tc16, tc2'. So the 'Alarm in Channels' and the 'Alarm Out' are left out. In total this would give 18 headers. (See picture in attachment for clarification)

I also would like to extract all the data in the rows beneath the headers. These numbers are seperated by a comma (comma delimiter) and in total there are also 18 numbers in 1 row. I am familiar using fopen and textscan, but I'm not sure how to use it to get what I would like to have...

Thank you

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Stephen23 2020-10-6

编辑：Stephen23 2020-10-6

"Can someone help me out please?"

Please upload some sample data that we can use (screenshots are pretty but quite useless) by clicking the paperclip button.

Sam 2020-10-6

I couldn't agree more. Apologies for the inconvenience. I've uploaded the data. Thank you!

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Answer 1

Stephen23 2020-10-6

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/606116-reading-textfile-using-fopen-and-textscan#answer_506321

编辑：Stephen23 2020-10-6

在 MATLAB Online 中打开

This reads your file:

opt = {'Delimiter',',', 'CollectOutput',true};
[fid,msg] = fopen('test_file.txt','rt');
assert(fid>=3,msg)
str = '';
while ~strcmpi(str,'[Channel Data]')
	str = strtrim(fgetl(fid));
end
str = fgetl(fid);
hdr = regexp(str,'[^,]+','match');
hdr(strncmpi(hdr,'Alarm',5)) = [];
tmp = repmat({'%f'},1,numel(hdr));
tmp{strcmpi(hdr,'Date&Time')} = '%s'; % or '%{MM/dd/yyyy HH:mm:ss:SSS}D' for datetime
fmt = [tmp{:},'%*[^\n]'];
out = textscan(fid,fmt,opt{:});
fclose(fid);

Giving:

>> out{1}
ans =
     1
     2
     3
     4
     5
     6
>> out{2}
ans = 
    '04/23/2020 19:42:52:000'
    '04/23/2020 19:42:53:000'
    '04/23/2020 19:42:54:000'
    '04/23/2020 19:42:55:000'
    '04/23/2020 19:42:56:000'
    '04/23/2020 19:42:57:000'
>> out{3}
ans =
    0.0194    0.0292    0.0089    0.0009    0.0119   20.0000   23.0000   22.8000   24.2000   24.3000   25.1000   24.9000   24.3000   24.8000   25.3000   22.4000
    0.0194    0.0292    0.0080    0.0006    0.0125   20.0000   23.0000   22.8000   24.2000   24.3000   25.1000   24.9000   24.3000   24.8000   25.3000   22.4000
    0.0191    0.0292    0.0071    0.0006    0.0131   20.0000   23.0000   22.7000   24.2000   24.3000   25.1000   25.0000   24.3000   24.8000   25.3000   22.4000
    0.0194    0.0292    0.0063    0.0006    0.0137   20.0000   23.0000   22.7000   24.2000   24.3000   25.1000   24.9000   24.3000   24.8000   25.3000   22.4000
    0.0197    0.0292    0.0054    0.0003    0.0143   20.0000   23.0000   22.7000   24.2000   24.3000   25.1000   24.9000   24.3000   24.8000   25.3000   22.4000
    0.0197    0.0289    0.0048    0.0003    0.0146   20.0000   23.0000   22.8000   24.2000   24.3000   25.1000   24.9000   24.3000   24.8000   25.3000   22.4000