MATLAB: How do you replicate textread functionality with textscan

textreadtextscan

I have been working with some code that reads in a text file using textread. The textread approach is simple and works perfectly for what I want. It reads in the text file and allows me to access each line by using a number – so line 176 is file(176).

This is what I used for textread:

inFile = textread('filename','%s','delimiter','\n');

The problem is that apparently textread is going to be removed in future versions and Matlab says to use textscan instead. However, I can't figure out how to replicate this functionality with textscan.

Using textscan, instead of data set that is indexable line by line, I get an entire data file in a single 1×1 cell.

This is the kind of thing I have been trying with textscan:

inFile = textscan(fid, '%s','EndOfLine','\n','Delimiter','\n')

I would greatly appreciate any help in getting the previous functionality.

Best Answer

If your cell array is data, then you can get each line you want

x=data{:}
line20=x(20,:)

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MATLAB: Limit to Textscan

Thanks for clarifying what your data looks like.

I assume that comma immediately after the '4' is a mistake. You could probably do this with a regexp... Because each comma denotes a pair of values. I take it that if the value before the comma is missing then the value after is also missing.

Do you have a fixed number of columns? If so, are the commas always there?

If at least the second condition above is true, then this isn't so bad... You can read pairs of values using regexp:

lines = {'1, 2  3, 4  5,  6'
         '1, 2  3, 4  5,  6'
         '1, 2  3, 4   ,  '
         ' ,    3, 4  , '};
toks = regexp(lines, '\s*(\w*)\s*,\s*(\w*)', 'tokens');

This extracts word-like strings with optional spaces and the obligatory comma.

What you end up with is one cell per row, and within that one cell per pairing. You can manipulate this data as you see fit, convert empty strings or non-numbers to NaN, etc...

I dunno, that's the kind of solution I come up with when I don't want to spend too much time thinking up more complicated clever stuff.

[EDIT]

The above regexp fails on the fourth line because there's no logic that says if you have the first value you must have the second (and vice versa)... So try this:

toks = regexp(lines, '\s*(\w+)\s*,\s*(\w+)|\s*()\s*,\s*()', 'tokens');
rows = cell(size(toks));
for r = 1:numel(toks)
  rows(r) = { str2double([toks{r}{:}]) };
end

Now you have a cell with one row per line, containing a vector of doubles...

This won't work with other rubbish in your data like % signs, but you can either filter that or allow for it in the regular expression....

And if course if you know that all your rows are the same length (or force them to be after processing), you can convert the whole rows array to a matrix with cell2mat

MATLAB: How to read a CSV file with header

The better way was use the textscan function with ";" delimiter and after replace the "," by "." before the conversion of string to number.

fileID = fopen(filename,'r');
startRow = 10;
dataArray = textscan(fileID,'%s%s%s',inf,'Delimiter',';',...
    'HeaderLines', startRow-1,'ReturnOnError', false);
fclose(fileID);
dataArray{1,2} = strrep(dataArray{1,2},',','.');
dataArray{1,3} = strrep(dataArray{1,3},',','.');

Best Answer

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MATLAB: Limit to Textscan

MATLAB: How to read a CSV file with header

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