Change empty string to "NaS" when reading from a file

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Madlab
Madlab 2018-9-27
评论： Bish Erbas 2018-9-27
I want to read from a text file which has certain blank string cells in it. However, the character data isn't a numeric value, so I cannot use 'emptyvalue',NaN Is there a similar way for textread to fill blank cells for string with 'NaS'(Not a String)? I have tried many methods to overcome this but I am still lost. I have read that using "%[^ ]" can ignore characters in the box but I get an error when using it. Am I using it the wrong way?
inFile = 'filepath';
% Extracting data from the input file
[a,b,c,d] = textread(inFile,'%*d %*s %*s %*s %*s %*s %*s %*s %f %f %*d %[^ ] %s','headerlines',2,'delimiter','\t','emptyvalue', NaN);
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Stephen23
Stephen23 2018-9-27
编辑：Stephen23 2018-9-27
Note: at the very top of the textread help page it states:
" textread is not recommended. Use textscan instead."
I would recommend following the advice in the MATLAB documentation.
"Am I using it the wrong way?"
You are using very outdated textread, instead of the reccomended textscan.
"However, I don't see any difference in what textscan would do as it still reads the data like textread."
You might not see any difference, but clearly the makers of MATLAB do, because they specifically advise against using it. Legacy functions, like textread, are not recommended for new code or projects.

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回答（1 个）

Bish Erbas
Bish Erbas 2018-9-27
You can import all data as into a string cell array A and then perform all required conversions.
f = fopen('file.txt');
A = textscan(f,'%s %s %s %s %s %s %s %s %s %s %s %s %s','headerlines',2,'delimiter','\t');
fclose(f);
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Stephen23
Stephen23 2018-9-27
"Not all the data inside the file is string too. There are some that are numbers."
So change the format string.
Bish Erbas
Bish Erbas 2018-9-27
Stephen is right. Mine is just a simple example. Replace %s with %d for the columns contain numeric values if you want to save a few lines of post-processing after the import.

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