How to skip lines when reading a text file that start with specific input?

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Marian 2014-11-14

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评论： Andrew Reibold 2014-11-26

Hi -

I'm working on reading in a text file of accumulated data, but the headerlines are always printed with the data. For example, the beginning of each line in the text file looks like:

"TOA5","CapeBird","CR1000",
"TIMESTAMP","RECORD",
"TS","RN","","","","",
"","","Smp","Smp","Smp"
"2014-10-01 00:10:00", 
"2014-10-01 00:20:00",
"2014-10-01 00:30:00", 
"TOA5","CapeBird","CR1000",
"TIMESTAMP","RECORD",
"TS","RN","","","","",
"","","Smp","Smp","Smp"
"2014-10-01 00:40:00", 
"2014-10-01 00:50:00",
"2014-10-01 01:00:00",

.....

I've found examples where you can specify to not read in strings through the "textscan" function, but as you can see, everything is a string. The data I want read in starts with the dates "2014-10-01..." and I want to eliminate the 4 lines that have words or just empty double quotes. The header will always be exactly the same... it's a very long line of text, so I'm not sure if that complicates this, or if I can just find the first phrase/word and eliminate the entire line. Also, the data is not always consistent and will not always come in lines of 3 (sometimes more, sometimes less), so I can't just skip 4 lines, read in 3, skip 4 lines, etc.

If anyone knows how I can delimit or just eliminate these 4 header lines by somehow checking for a word/phrase/entire line, that would be incredibly helpful. Long story short, when the line is NOT one of the header lines, I need this to work:

textscan(file,'%s %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f %f', ...
        'delimiter',',','EmptyValue',nan, 'headerLines',4,'TreatAsEmpty','"NAN"')

Thanks!

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Answer 1

Andrew Reibold 2014-11-14

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https://ww2.mathworks.cn/matlabcentral/answers/162722-how-to-skip-lines-when-reading-a-text-file-that-start-with-specific-input#answer_159010

编辑：Andrew Reibold 2014-11-14

Hi Marian,

Maybe this can get you started. I made a textfile of the example you provided, and a sample code is attached to read it.

What this is doing is reading each line, checking if it has the right date, and then if it does - perform 'some action' . Right now, as an example I have it just saving the desired strings to a new cell called Clean_Data. If you wanted, I'm sure you could replace my example action with your textscan command here. :)

Let me know if you have a question. I did not incorporate your specific textscan line because the example data is not a full sample with the right format.

Edit: Will not be available this weekend. Best wishes though

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Marian 2014-11-21

Thanks so much! I had to generalize the code slightly (So that it can work for all months, not just Oct, and all dates, not just the 1st), but this definitely solved my problem!

Andrew Reibold 2014-11-26

Oops. Yeah, hard coding the date was pretty dumb! Good job!

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How to skip lines when reading a text file that start with specific input?

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