MATLAB Answers


readData() function error message when using mapreduce

Asked by Rómulo Alves on 5 Aug 2019
Latest activity Commented on by Rómulo Alves on 6 Aug 2019
I have a very large file (100's of millions of data points) and I am using mapreduce and datastore to get access to specifc chunks of data.
I get the following error (below) when I run it and I do not know how to go around it. lAny suggestions on how to deal with this?
Error using (line 81)
Mismatch between file and format character vector.
Trouble reading 'Numeric' field from file (row number 1136, field number 15) ==>
Error in (line 120)
[t, info] = readData(ds);
Error in (line 7)
[varargout{1 : nargout}] = read(ds);
Error in mapreduce (line 116)
outds = execMapReduce(mrcer, ds, mapfun, reducefun, parsedStruct);
Caused by:
Reading the variable name 'ticker' using format '%f' from file


Sign in to comment.

1 Answer

Answer by Jeremy Hughes on 5 Aug 2019
 Accepted Answer

ds.TextscanFormats{15} = '%q'
That will at least get you past the one line that's causing the problem here. For a more robust answer, I'd have to look at the file. It could be that there's an error in a line somewhere that's throwing off the parsing.


thank you! does this imply any loss of information ?
Nope, %f is trying to read numbers, and if there isn't a number, it errors. %q reads (possibly double quoted) strings--it cannot really error.

Sign in to comment.