I want to have a look at a large matrix in MATLAB such that all columns are printed in one single line rather than spread out over several lines.
Is such thing possible? That would be great to know.
Try disp(matrixName(:)). The matrixName(:) command turns your matrix into a long vector in column-major order, so it basically just shows you the first column, followed by the second, the third, etc.
If that does not do the trick, you could look into the doprint command.
EDIT: You could also save the matrix to a text file and view the file. You do this like so:
fileID = fopen('C:/path/to/file/myMatrix.txt');
fprintf(fileID, formatString, myMat);
fclose(fileID);
fopen documentation
fprintf documentation
Additional information can be found here
The formatString variable in the above tells fprintf how the data should be displayed. If you have a really big matrix with tons of columns, where all of the values are floats, the easiest way to create this string is to use something like:
formatString = strcat(repmat('%f ', 1, size(myMat, 2)), '\n');
This will create a long string specifying that each element in your matrix is a float, and where it goes, and then cap it off with a line feed so that the next row of your matrix starts on the next line.
Suppress your original matrix with a semicolon and then use the "disp" command to show your matrix however you want.
for i = 1 : length(matrix(1,:))
disp(matrix(:,i))
end
Some "obvious" answers:
You can choose a smaller font - then more values will fit in a line
You can play with the format command to have less digits displayed
(my favourite) Use the variable viewer - via "open selection" or Ctrl-D when the name of a variable is highlighted. This will show your matrix in an excel-like table.
Related
I am very new to MATLAB and i am currently trying to learn how to import files in matlab and work on it. I am importing a "*.dat" file which contains a single column of floating point numbers[they are just filter coefficients I got from a c++ code] into an array in MATLAB. When I am displaying the output in command window the first line is always " 1.0e-03 * " followed by the contents of my file. I want to know what it means? When I check my workspace the array connects the correct number of inputs. My sample code and first few lines of output are below:
Code:-
clear; clc;
coeff = fopen('filterCoeff.dat');
A = fscanf(coeff, '%f');
A
fclose(coeff);
Output:-
A =
**1.0e-03 *** <===== What does this mean?
-0.170194000000000
0
0.404879000000000
0
-0.410347000000000
P.S: I found many options to read file eg. textscan, fscanf etc. Which one is the best to use?
It is a multiplier that applies to all the numbers displayed after that. It means that, for example, the last entry of A is not -0.410347 but -0.410347e-3, that is, -0.000410347.
I think it is is just Matlab's display number type. It means each of your results are scaled by that amount.
format longg
A
And see what it displays. Look at the docs for format for other options.
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.
does anyone know how to save an uint8 workspace variable to a txt file?
I tried using MATLAB save command:
save zipped.txt zipped -ascii
However, the command window displayed warning error:
Warning: Attempt to write an unsupported data type to an ASCII file.
Variable 'zipped' not written to file.
In order to write it, simply cast your values to double before writing it.
A=uint8([1 2 3])
toWrite=double(A)
save('test.txt','toWrite','-ASCII')
The reason uint8 can't be written is hidden in the format section of the save doc online, took myself a bit to find it.
The doc page is here: http://www.mathworks.com/help/matlab/ref/save.html
The 3rd line after the table in the format section (about halfway down the page) says:
Each variable must be a two-dimensional double or character array.
Alternatively, dlmwrite can write matrices of type uint8, as the other poster also mentioned, and I am sure the csv one will work too, but I haven't tested it myself.
Hopefully that will help you out, kinda annoying though! I think uint8 is used almost exclusively for images in MATLAB, but I am assuming writing the values as an image is not feasible in your situation.
have you considered other write-to-file options in Matlab?
How about dlmwrite?
Another option might be cvswrite.
For more information see this document.
Try the following:
%# a random matrix of type uint8
x = randi(255, [100,3], 'uint8');
%# build format string
frmt = repmat('%u,',1,size(x,2));
frmt = [frmt(1:end-1) '\n'];
%# write matrix to file in one go
f = fopen('out.txt','wt');
fprintf(f, frmt, x');
fclose(f);
The resulting file will be something like:
16,108,149
174,25,138
11,153,222
19,121,68
...
where each line corresponds to a matrix row.
Note that this is much faster than using dlmwrite which writes one row at a time
I've been fighting with fprintf for an hour now, should be easy but it's not apparently.
Have a vector with descriptive statistics called datasave, contains 9 numbers like average, standard dev, kurtosis etc.
And I have a vector datalabels with the lablels 'Average' , 'St.dev', 'Kurt' etc.
Open a file with fileopen
print the labels
new line
print the values ( exactly under the labels!)
close the file
This is what I've tried so far:
fileID = fopen('descstat2.txt','w');
fprintf(fileID,'MediaTonnes MinTonnes MaxTonnes Sigma Skew Kurt SigmadTonnes SkewdTonnes KurtdTonnes\r\n');
format short;
fprintf(fileID, '%g\t%g\t%g\n', datasave.');
Help?
I have at least 50 different combinations so I can't really give you my output...
Maybe try this:
fileID = fopen('descstat2.txt','w');
fprintf(fileID,'%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\t%s\r\n', datalabels);
fprintf(fileID, '%g\t%g\t%g\t%g\t%g\t%g\t%g\t%g\t%g\r\n', datasave);
fclose
To use XLSWRITE you need to create a cell array:
out = [datalabels(:)'; num2cell(datasave)];
xlswrite('descstat2', out)
If the file you are saving to is exist as a text file, xlswrite will save it as a text as well.
It probably will be slower that fprintf (due to COM interface) but you don't have to deal with formatting the output. Just need to convert everything to cells.
Another option is to use TBLWRITE from Statistical Toolbox. You can just do:
tblwrite(datasave, datalabels, [], filename, '\t')
It will also put row numbers or labels specified as 3rd argument. Might be useful for some data.
I've written a script that saves its output to a CSV file for later reference, but the second script for importing the data takes an ungainly amount of time to read it back in.
The data is in the following format:
Item1,val1,val2,val3
Item2,val4,val5,val6,val7
Item3,val8,val9
where the headers are on the left-most column, and the data values take up the remainder of the row. One major difficulty is that the arrays of data values can be different lengths for each test item. I'd save it as a structure, but I need to be able to edit it outside the MATLAB environment, since sometimes I have to delete rows of bad data on a computer that doesn't have MATLAB installed. So really, part one of my question is: Should I save the data in a different format?
Second part of the question:
I've tried importdata, csvread, and dlmread, but I'm not sure which is best, or if there's a better solution. Right now I'm using my own script using a loop and fgetl, which is horribly slow for large files. Any suggestions?
function [data,headers]=csvreader(filename); %V1_1
fid=fopen(filename,'r');
data={};
headers={};
count=1;
while 1
textline=fgetl(fid);
if ~ischar(textline), break, end
nextchar=textline(1);
idx=1;
while nextchar~=','
headers{count}(idx)=textline(1);
idx=idx+1;
textline(1)=[];
nextchar=textline(1);
end
textline(1)=[];
data{count}=str2num(textline);
count=count+1;
end
fclose(fid);
(I know this is probably terribly written code - I'm an engineer, not a programmer, please don't yell at me - any suggestions for improvement would be welcome, though.)
It would probably make the data easier to read if you could pad the file with NaN values when your first script creates it:
Item1,1,2,3,NaN
Item2,4,5,6,7
Item3,8,9,NaN,NaN
or you could even just print empty fields:
Item1,1,2,3,
Item2,4,5,6,7
Item3,8,9,,
Of course, in order to pad properly you would need to know what the maximum number of values across all the items is before hand. With either format above, you could then use one of the standard file reading functions, like TEXTSCAN for example:
>> fid = fopen('uneven_data.txt','rt');
>> C = textscan(fid,'%s %f %f %f %f','Delimiter',',','CollectOutput',1);
>> fclose(fid);
>> C{1}
ans =
'Item1'
'Item2'
'Item3'
>> C{2}
ans =
1 2 3 NaN %# TEXTSCAN sets empty fields to NaN anyway
4 5 6 7
8 9 NaN NaN
Instead of parsing the string textline one character at a time. You could use strtok to break the string up for example
stringParts = {};
tline = fgetl(fid);
if ~ischar(tline), break, end
i=1;
while 1
[stringParts{i},r]=strtok(tline,',');
tline=r;
i=i+1;
if isempty(r), break; end
end
% store the header
headers{count} = stringParts{1};
% convert the data into numbers
for j=2:length(stringParts)
data{count}(j-1) = str2double(stringParts{j});
end
count=count+1;
I've had the same problem with reading csv data in Matlab, and I was surprised by how little support there is for this, but then I just found the import data tool. I'm in r2015b.
On the top bar in the "Home" tab, click on "Import Data" and choose the file you'd like to read. An app window will come up like this:
Import Data tool screenshot
Under "Import Selection" you have the option to "generate function", which gives you quite a bit of customization options, including how to fill empty cells, and what you'd like the output data structure to be. Plus it's written by MathWorks, so it's probably utilizing the fastest available method to read csv files. It was almost instantaneous on my file.
Q1) If you know the max number of columns you can fill empty entries with NaN
Also, if all values are numerical, do you really need "Item#" column? If yes, you can use only "#", so all data is numerical.
Q2) The fastest way to read num. data from a file without mex-files is csvread.
I try to avoid using strings in csv files, but if I have to, I use my csv2cell function:
http://www.mathworks.com/matlabcentral/fileexchange/20135-csv2cell