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Read txt file with comma decimal separator in MATLAB [duplicate]
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I have this data from a radiation diagram of an antenna in a txt file:
And the text continues. As you see, the integer and decimal part of numbers are separated by commas, instead of points. Moreover, I don't need the first row since they aren't values. I have tried using this code:
file = fread('file.txt')
data = fread(file)
fclose(file)
However, all the data was in a vector, so I tried to visualise a little part of the file, writing data = fread(file, [20,4]). Nevertheless, the data was wrong, here's what I obtained:
I also tried with fscanf function, but I didn't work either. I'd like to open the entire file (without knowing the number of elements previously).
I hope someone can help me. Thank you for your responses.
You can specify the delimiter in many data reading functions so it's not a comma, I find readtable the simplest:
T = readtable( 'file.txt', 'Delimiter', 'tab' );
It looks like your data is tab separated, so use the 'tab' option. You could also use 'space' or any given character.
Comma-formatted decimals can then be converted
c = T.Properties.VariableNames;
for ii = 1:numel(c)
t.(c{ii}) = cellfun( #(x)str2double(strrep(x,',','.')), t.(c{ii}) );
end
Related
I have been trying in vain for days to do one seemingly simple thing--I want to read data from a .txt file that looks like this:
0.221351321
0.151351321
0.235165165
8.2254546 E-7
into Matlab. I've been able to load the data in the .txt file as a column vector using the fscanf command, like so:
U=fscanf(FileID, '%e')
provided that I go through the file first and remove the space before the 'E' wherever scientific notation occurs in the data set.
Since I have to generate a large number of such sets, it would be impractical to have to do a search-and-replace for every .txt file.
Is there a way for matlab to read the data as it appears, as in the above example (with the space preceding 'E'), and put it into a column vector?
For anyone who knows PARI-GP, an alternate fix would be to have the output devoid of spaces in the first place--but so far I haven't found a way to erase the space before 'E' in scientific notation, and I can't predict if a number in scientific notation will appear or not in the data set.
Thank you!
Thank you all for your help, I have found a solution. There is a way to eliminate the space from PARI-GP, so that the output .txt file has no spaces to begin with. I had the output set to "prettymatrix". One needs to enter the following:
? \o{0}
to change the output to "Raw," which eliminates the space before the "E" in scientific notation.
Thanks again for your help.
A simple way, may not be the best, is to read line by line, remove the space and convert back to floating point number.
For example,
x = []
tline = fgetl(FileID);
while ischar(tline)
x = [x str2num(tline(find(~isspace(tline))))]
tline = fgetl(FileID);
end
One liner:
data = str2double(strsplit(strrep(fileread('filename.txt'),' ',''), '\n'));
strrep removes all the spaces, strsplit takes each line as a separate string, and str2double coverts the strings to numbers.
I have a fixed width file format (original was input for a Fortran routine). Several lines of the file look like the below:
1078.0711005.481 932.978 861.159 788.103 716.076
How this actually should read:
1078.071 1005.481 932.978 861.159 788.103 716.076
I have tried various methods, textscan, fgetl, fscanf etc, however the problem I have is, as seen above, sometimes because of the fixed width of the original files there is no whitespace between some of the numbers. I cant seem to find a way to read them directly and I cant change the original format.
The best I have come up with so far is to use fgetl which reads the whole line in, then I reshape the result into an 8,6 array
A=fgetl
A=reshape(A,8,6)
which generates the following result
11
009877
703681
852186
......
049110
787507
118936
So now I have the above and thought I might be able to concatenate the rows of that array together to form each number, although that is seeming difficult as well having tried strcat, vertcat etc.
All of that seems a long way round so was hoping for some better suggestions.
Thanks.
If you can rely on three decimal numbers you can use a simple regular expression to generate the missing blanks:
s = '1078.0711005.481 932.978 861.159 788.103 716.076';
s = regexprep(s, '(\.\d\d\d)', '$1 ');
c = textscan(s, '%f');
Now c{1} contains your numbers. This will also work if s is in fact the whole file instead of one line.
You haven't mentioned which class of output you needed, but I guess you need to read doubles from the file to do some calculations. I assume you are able to read your file since you have results of reshape() function already. However, using reshape() function will not be efficient for your case since your variables are not fixed sized (i.e 1078.071 and 932.978).
If I did't misunderstand your problem:
Your data is squashed in some parts (i.e 1078.0711005.481 instead
of 1078.071 1005.481).
Fractional part of variables have 3 digits.
First of all we need to get rid of spaces from the string array:
A = A(~ismember(A,' '));
Then using the information that fractional parts are 3 digits:
iter = length(strfind(A, '.'));
for k=1:iter
[stat,ind] = ismember('.', A);
B(k)=str2double(A(1:ind+3));
A = A(ind+4:end);
end
B will be an array of doubles as a result.
What I have
A txt file like:
D091B
E7E1F
20823
...
What I need
To read them and store them like char, just as they are in the file: N (don't knot how many) lines, with its 5 characters (5 columns) at each one.
What have I tried
fichero = fopen('PS.txt','r');
sizeDatos = [[] 5]; % Several Options, read below
resultados=fscanf(fichero, '%s', sizeDatos); % Here too
fclose(fichero);
I've tried with the snippet above, to read my txt file. However, I didn't manage to get it. Most I've obtained is, using:
sizeDatos = [1 Inf];
So I got all my hex characters into an array, with no spaces.
As you can see, I've tried several optios changing fscanf size parameter, as well as trying to say into the format chain that it should recognize new lines by using \n for example. None of them have worked for me.
Any idea about how can I get it? I've readed fscanf page from documentation, but it didn't inspire me to make anything different.
One possible solution is using textscan and convert it to a cell array.
fileId = fopen('PS.txt');
C = textscan(fileId, '%s');
Now to show the content of cell you can use
celldisp(C)
Or you can convert it to other types.
Don't forget to close your file after using it.
I have a tab delimited text file with suffix .RAW.
How can I load the data from the file into a matrix in MATLAB?
I have found readtable, but it doesn't support files ending with suffix .RAW.
Do I really have to use fread, fscanf, etc. to simply load a text file into a matrix?
You can use the dlmread() function. It will read data from an ASCII text file into a matrix and let you define the delimiter yourself. The delimiter for tabs is '\t'.
>> M = dlmread('Data.raw', '\t')
M =
1 2 3
4 5 6
7 8 9
Just for your information there is also the tdfread() function but I do not recommend using it except in very specific cases. dlmread() is a much better option.
.RAW is a generic file extention. You should know the format of your RAW file (especially if your file contains a combination of numbers, data structures etc). If it is a simple text file with a single 2D table, you can easily read it with fscanf, fread, fgetl, fgets, etc
Here is a simple example for a 2D table (matrix):
Let's assume that each row of your table is separated by a carriage return from its following rows. We can read each row by fgetl() and then extract numbers using str2num().
fid=fopen('YourTextFile.RAW');
Data=[];
i = 0;
while 1
i = i + 1;
tline = fgetl(fid);
if ~ischar(tline), break, end
Data(i,:) = str2num(tline);
end
fclose(fid);
disp(Data)
For more complex data structure, the code should be changed.
For a 2D table (a special case) the above simple code can be easily exchanged by dlmread() function.
I have decided to use memmapfile because my data (typically 30Gb to 60Gb) is too big to fit in a computer's memory.
My data files consist two columns of data that correspond to the outputs of two sensors and I have them in both .bin and .txt formats.
m=memmapfile('G:\E-Stress Research\Data\2013-12-18\LD101_3\EPS/LD101_3.bin','format','int32')
m.data(1)
I used the above code to memory map my data to a variable "m" but I have no idea what data format to use (int8', 'int16', 'int32', 'int64','uint8', 'uint16', 'uint32', 'uint64', 'single', and 'double').
In fact I tried all of the data formats listed that MATLAB supports, but when I used the m.data(index number) I never get a pair of numbers (2 columns of data) which is what I expected, also the number will be different depending on the format I used.
If anyone has experience with memmapfile please help me.
Here are some smaller versions of my data files so people can understand how my data is structured:
cheers
James
memmapfile is designed for reading binary files, that's why you are having trouble with your text file. The data in there is characters, so you'll have to read them as characters and then parse them into numbers. More on that below.
The binary file appears to contain more than just a stream of floating point values written in binary format. I see identifiers (strings) and other things in the file as well. Your only hope of reading that is to contact the manufacturer of the device that created the binary file and ask them about how to read in such files. There'll probably be an SDK, or at least a description of the format. You might want to look into this as the floating point numbers in your text file might be truncated, i.e., you have lost precision compared to directly reading the binary representation of the floats.
Ok, so how to read your file with memmapfile? This post provides some hints.
So first we open your file as 'uint8' (note there is no 'char' option, so as a workaround we read the content of the file into a datatype of the same size):
m = memmapfile('RTL5_57.txt','Format','uint8'); % uint8 is default, you could leave that off
We can render the data read in as uint8 as characters by casting it to char:
c = char(m.Data(1:19)).' % read the first three lines. NB: transpose just for getting nice output, don't use it in your code
c =
0.398516 0.063440
0.399611 0.063284
0.398985 0.061253
As each line in your file has the same length (2*8 chars for the numbers, 1 tab and 2 chars for newline = 19 chars), we can read N lines from the file by reading N*19 values. So m.Data(1:19) gets you the first line, m.Data(20:38), the second line, and m.Data(20:57) the second and third lines. Read as much as you want at once.
Then we'll have to parse the read-in data into floating point numbers:
f = sscanf(c,'%f')
f =
0.3985
0.0634
0.3996
0.0633
0.3990
0.0613
All that's left now is to reshape them into your two column format
d = reshape(f,2,[]).'
d =
0.3985 0.0634
0.3996 0.0633
0.3990 0.0613
Easier ways than using memmapfile:
You don't need to use memmapfile to solve your problem, and I think it makes things more complicated. You can simply use fopen followed by fread:
fid = fopen('RTL5_57.txt');
c = fread(fid,Nlines*19,'*char');
% now sscanf and reshape as above
% NB: one can read the values the text file directly with f = fscanf(fid,'%f',Nlines*19).
% However, in testing, I have found calling fread followed by sscanf to be faster
% which will make a significant difference when reading such large files.
Using this you can read Nlines pairs of values at a time, process them and simply call fread again to read the next Nlines. fread remembers where it is in the file (as does fscanf), so simply use same call to get next lines. Its thus easy to write a loop to process the whole file, testing with feof(fid) if you are at the end of the file.
An even easier way is suggested here: use textscan. To slightly adapt their example code:
Nlines = 10000;
% describe the format of the data
% for more information, see the textscan reference page
format = '%f\t%f';
fid = fopen('RTL5_57.txt');
while ~feof(fid)
C = textscan(fid, format, Nlines, 'CollectOutput', true);
d = C{1}; % immediately clear C at this point if you need the memory!
% process d
end
fclose(fid);
Note again however that the fread followed by sscanf will be fastest. Note however that the fread method would die as soon as there is one line in the text file that doesn't exactly match your format. textscan is forgiving of whitespace changes on the other hand and thus more robust.