GNU Octave: reading data with NA values using textscan(...)

Question

I need to read data from an ASCII file where missing values are given as NA. Using textscan(...) does not seem to work, because textscan(...) seems to stop reading/parsing at the first occurrence of NA.

Here's a simple demonstration of the issue:

x = textscan ( "1 ; 2 ; 3\n4 ; NA ; 6" , '%d %d %d' , 'Delimiter' , ';' , 'ReturnOnError' , false )
error: textscan: Read error in field 2 of row 2

I have also tried to tell textscan(...) to interpret NA as "empty value", but no luck:

x = textscan ( "1 ; 2 ; 3\n4 ; NA ; 6" , '%d %d %d' , 'Delimiter' , ';' , 'TreatAsEmpty' , 'NA' , 'ReturnOnError' , false )
error: textscan: Read error in field 2 of row 2

Can someone explain what's going on, or how to make this work?

Note that is just a simplified example to illustrate the problem. The format of the data in my files is a bit more complex, and I really depend on textscan(...) to parse it; I don't think I can easily do it without textscan(...).

(I am running Octave 4.2.1.)

score 2 · Accepted Answer · answered Feb 09 '18 at 11:17

2

NA is defined for floating point numbers so you should use '%f' conversion specifier instead of '%d'.

x = textscan ( "1 ; 2 ; 3\n4 ; NA ; 6" , '%f %f %f' ,
    'Delimiter' , ';' , 'ReturnOnError' , false )

answered Feb 09 '18 at 11:17

rahnema1

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This is not consistent with MATLAB though. :/ Tested in both MATLAB and Octave. Works in Octave. – Sardar Usama Feb 09 '18 at 12:32
@SardarUsama Thanks, I think `NaN` should be used instead of `NA` can you test it? – rahnema1 Feb 09 '18 at 12:37
@SardarUsama If `%d` is used NA is converted to `0` instead of `NaN`. – rahnema1 Feb 09 '18 at 12:40
In MATLAB, problem is caused by `\n`. See here: [#1](https://i.stack.imgur.com/iAPln.jpg) and [#2](https://i.stack.imgur.com/aCcyy.jpg) – Sardar Usama Feb 09 '18 at 12:47
[*.*](https://i.stack.imgur.com/nJK47.jpg) Anyway, your answer is fine and correct as it is since the question is asked about Octave – Sardar Usama Feb 09 '18 at 13:02

GNU Octave: reading data with NA values using textscan(...)

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