Read mixed numbers in Matlab

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John Smith
John Smith on 22 Dec 2018
Commented: Stephen on 30 Dec 2018
Dear Sir/Madam,
I have a data file containing text and mixed number like this: (see the file attached data.txt.)
AA, BB, 28 21/64, 28 45/64,
AA, BB, 1/64, 11/64,
the mixed number have format:
integer space numerator/denominator
I would like to read the data file in matlab as
AA, BB, 28.328125, 28.703125,
AA, BB, 0.015625, 0.171875,
i. e. read mixed numbers and convert them into decimal numbers.
What Matlab command to use? I would greatly appreciate it if you left your code and running output.
I am using MATLAB R2014a.
Thank you

Accepted Answer

Stephen
Stephen on 23 Dec 2018
Edited: Stephen on 23 Dec 2018
opt = {'CollectOutput',true,'Delimiter',','};
fmt = repmat('%s',1,4);
[fid,msg] = fopen('data.txt','rt');
assert(fid>=3,msg);
C = textscan(fid,fmt,opt{:})
fclose(fid);
C = C{1}; % raw character data in a cell array.
% Convert fractions to numeric:
foo = @(v) sum([v(1:end-2),v(end-1)/v(end)]);
baz = @(s) foo(sscanf(s,'%d%*[ /]'));
M = cellfun(baz,C(:,3:4))
Giving:
M =
28.328125 28.703125
0.031250 0.046875
and the string data is in C. If you want the numeric data reinserted back into C then use num2cell:
>> C(:,3:4) = num2cell(M)
C =
'AA' 'CC' 28.328125 28.703125
'AA' 'CC' 0.031250 0.046875
  14 Comments
Stephen
Stephen on 30 Dec 2018
@John Smith: that is quite a different topic. Please ask a new question about that.

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More Answers (2)

Brian Hart
Brian Hart on 22 Dec 2018
Here's some code to read the data in as a table, then update the mixed number values in each row to the decimal...
T = readtable("C:\Users\MATLAB\Desktop\data.txt",'Delimiter',',','ReadVariableNames',false)
numRows = size(T,1);
for i = 1:numRows
for j=3:4
tmpstr = T{i,j};
tmpstr=tmpstr{:};
tmpstr=strrep(tmpstr, '/',' ');
mixedVal = sscanf(tmpstr,'%d');
if size(mixedVal,1) == 2
decVal = mixedVal(1)/mixedVal(2);
else
decVal = mixedVal(1) + mixedVal(2)/mixedVal(3);
end
T(i,j) = {num2str(decVal)};
end
end
disp(T)
  1 Comment
John Smith
John Smith on 23 Dec 2018
Thank you Brian,
The code give me those errors: (I am using Matlab R2014a)

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Guillaume
Guillaume on 22 Dec 2018
Edited: Guillaume on 24 Dec 2018
I would recommend that you modify whatever is creating these files so that it creates files that don't have such an unusual format.
As it is, the following should work but is not particularly good code:
data = readtable('data.txt', 'Delimiter', ',', 'ReadVariableNames', false);
data = [data(:, [1 2]), ... %leave text variables unchanged
varfun(@(var) cellfun(@(var) str2num(strrep(var, ' ', '+')), var), data, 'InputVariables', [3 4])]; %convert 'numeric' variables
It simply replaces the space by + and use num2str to parse the expression which is simple but dangerous.
edited to add missing input to cellfun and wrong function use
  3 Comments
Guillaume
Guillaume on 24 Dec 2018
John wrote in a comment now deleted: "Could you please make your code also apply to decimal numbers (as well as mixed number). The reason is that some data has mixed numbers, some data use decimal numbers. I would like have one code fits all. "
As I pointed out, my answer already does that. In a much simpler way. Also note that the numeric columns are stored as vectors which is more memory efficient and easier to use than a cell array of scalars.

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