How to import a particular text file and plot.
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Here is the data that I wish to import:
Scan(+/- seconds),Sensor1Value,Sensor2Value,Sensor3Value,Sensor4Value
-1, 2, 8, 3, 4
'#' Comment Here
9, 0, 5, 6, 7
-------------------------------------
If I want to plot this kind of data,
fid = fopen(file.txt');
% read column headers
header = textscan(fid, '%s', 5, 'delimiter', ',', ... 'commentStyle', '#');
% read numeric data
data = textscan(fid, '%f %f %f %f %f', 'delimiter', ',', ... 'commentStyle', '#');
fclose(fid);
------------
My question is, when I type in header{1} I get all five columns. Shouldn't it be the case that if I type in header{1}, header{2}, header{3},...,header{5} I should get: Scan, Sensor1Value, Sensor2Value,...,Sensor4Value respectively?
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Accepted Answer
Matt Tearle
on 21 Sep 2012
Edited: Matt Tearle
on 21 Sep 2012
By specifying a format string of '%s', you effectively asked textscan for a single output. But then you asked to read a string 5 times. Consequently output is a single cell which contains five things. Those five things are themselves cells, which contain the strings you want. (Confused?)
So to get the third header, do
header{1}{3}
Or, you could do
textscan(fid, '%s%s%s%s%s', 1, ...
In which case you will get back 5 cells. But then each of them contains a single cell (which contains a string)!
Unfortunately this is just the way textscan works. It makes sense for reading whole columns of data, but not so much for a header line.
You can always do what you were doing and add
header = header{1}
Or do it the other way I showed above and add
header = [header{:}]
Either way, then, header will be a 5-element cell array of the strings.
EDIT, attempting to clarify: textscan returns an n-element cell array, where n is the number of format specifiers in the format string. Each cell will contain the contents that were read from the file. If the contents were numeric, you'll just get a numeric array. But if they were strings, you'll get a cell array of strings. That's why you're ending up with cell arrays containing cell arrays.
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