I want to convert an
fprintf output into a single array column and store into A
Additional Note: the Pij is a sparse matrix
for m = 1:nl
p = fb(m); q = tb(m);
fprintf('%8.3f\n', full(Pij(p,q)))
end
I'm trying the below code but it does not work. Appreciate your prompt solution as soon as possible . Thanks
A=sprintf('%8.3f\n', full(Pij(p,q)))
Related
I am currently working with a script that saves matrices as .mat files from other .mat files. I need to save 96 separate files so I have a loop that goes through the matrix names. I need to have the matrices saved with specific titles, that I have saved the titles in cell arrays {}. However, when I use the save(filename,variable) function, I get an error saying:
Error using save
Must be a text scalar.
Error in File_Creator (line 35)
save(name,fname);
My matrices need to be named 'PHI_Af','PHI_Am' (so on until) 'SLR_EF' (so every cr value needs to have a matrix with every par value. Here is what I am currently attempting:
cr = {'Af','Am','As','Aw','BS','BW','Cs','Cw','Cf','Ds','Dw','Df','ET','EF'};
par = {'PHI','BLD','KS','LAMBDA','PSIS','SLR'};
underscore = {'_'};
%% i and j are parameters in a loop where i = 1:length(par) and j = 1:length(cr)
%% f is the variable currently storing the matrix
s.(horzcat(par{i},underscore{1},cr{j})) = f;
name = string(strcat(par{i},'_',cr{j},'.mat'));
fname = string(s.(horzcat(par{i},underscore{1},cr{j})));
save(name,fname);
When I replace 'fname' with a generic string e.g. 'f', then the command runs but all the matrices save as the same thing ('f'), which makes it extremely difficult to run them all in the same script later.
I hope somebody can tell me what I'm doing wrong or provide me with a better solution. Please let me know if I can provide any more information.
Thank you
Assuming that the matrix, f, changes in each iteration of the loop (due to some other code you didn't post), it seems like this is all the code you need:
cr = {'Af','Am','As','Aw','BS','BW','Cs','Cw','Cf','Ds','Dw','Df','ET','EF'};
par = {'PHI','BLD','KS','LAMBDA','PSIS','SLR'};
for i = 1:length(par)
for j = 1:length(cr)
% add code here that loads the matrix f
name = [par{i}, '_', cr{j}, '.mat'];
save(name, 'f');
end
end
very very new to Matlab and I'm having trouble reading a binary file into a matrix. The problem is I am trying to write the binary file into a two column matrix (which has 100000's of rows) where each column is a different format type.
I want column 1 to be in 'int8' format and column 2 to be a 'float'
This is my attempt so far:
FileID= fopen ('MyBinaryFile.example');
[A,count] = fread(FileID,[nrows, 2],['int8','float'])
This is not working because I get the error message 'Error using fread' 'Invalid Precision'
I will then go on to plot once I have successfully done this.
Probably a very easy solution to someone with matlab experience but I haven't been successful at finding a solution on the internet.
Thanks in advance to anyone who can help.
You should be aware that Matlab cannot hold different data type in a matrix (it can do so in a cell array but this is another topic). So there is no point trying to read your mixed type file in one go in one single matrix ... it is not possible.
Unless you want a cell array, you will have to use 2 different variables for your 2 columns of different type. Once this is established, there are many ways to read such a file.
For the purpose of the example, I had to create a binary file as you described. This is done this way:
%% // write example file
A = int8(-5:5) ; %// a few "int8" data
B = single(linspace(-3,1,11)) ; %// a few "float" (=single) data
fileID = fopen('testmixeddata.bin','w');
for il=1:11
fwrite(fileID,A(il),'int8');
fwrite(fileID,B(il),'single');
end
fclose(fileID);
This create a 2 column binary file, with first column: 11 values of type int8 going from -5 to +5, and second column: 11 values of type float going from -3 to 1.
In each of the solution below, the first column will be read in a variable called C, and the second column in a variable called D.
1) Read all data in one go - convert to proper type after
%% // Read all data in one go - convert to proper type after
fileID = fopen('testmixeddata.bin');
R = fread(fileID,'uint8=>uint8') ; %// read all values, most basic data type (unsigned 8 bit integer)
fclose(fileID);
R = reshape( R , 5 , [] ) ; %// reshape data into a matrix (5 is because 1+4byte=5 byte per column)
temp = R(1,:) ; %// extract data for first column into temporary variable (OPTIONAL)
C = typecast( temp , 'int8' ) ; %// convert into "int8"
temp = R(2:end,:) ; %// extract data for second column
D = typecast( temp(:) , 'single' ) ; %// convert into "single/float"
This is my favourite method. Specially for speed because it minimizes the read/seek operations on disk, and most post calculations are done in memory (much much faster than disk operations).
Note that the temporary variable I used was only for clarity/verbose, you can avoid it altogether if you get your indexing into the raw data right.
The key thing to understand is the use of the typecast function. And the good news is it got even faster since 2014b.
2) Read column by column (using "skipvalue") - 2 pass approach
%% // Read column by column (using "skipvalue") - 2 pass approach
col1size = 1 ; %// size of data in column 1 (in [byte])
col2size = 4 ; %// size of data in column 2 (in [byte])
fileID = fopen('testmixeddata.bin');
C = fread(fileID,'int8=>int8',col2size) ; %// read all "int8" values, skipping all "float"
fseek(fileID,col1size,'bof') ; %// rewind to beginning of column 2 at the top of the file
D = fread(fileID,'single=>single',col1size) ; %// read all "float" values, skipping all "int8"
fclose(fileID);
That works too. It works fine ... but probably much slower than above. Although it may be clearer code to read for someone else ... I find that ugly (and yet I've used this way for several years until I got to use the method above).
3) Read element by element
%% // Read element by element (slow - not recommended)
fileID = fopen('testmixeddata.bin');
C=[];D=[];
while ~feof(fileID)
try
C(end+1) = fread(fileID,1,'int8=>int8') ;
D(end+1) = fread(fileID,1,'single=>single') ;
catch
disp('reached End Of File')
end
end
fclose(fileID);
Talking about ugly code ... that does work too, and if you were writing C code it would be more than ok. But in Matlab ... please avoid ! (well, your choice ultimately)
Merging in one variable
If really you want all of that in one single variable, it could be a structure or a cell array. For a cell array (to keep matrix indexing style), simply use:
%% // Merge into one "cell array"
Data = { C , D } ;
Data =
[11x1 int8] [11x1 single]
I am trying to copy the results to a matrix and want the output in a 32768*8 array. This is the code I am using, but it stops working after the last line.
As you can see for the first file ( i=1), the decimal data,T(32768*1) is converted to M(32768*8). Now I want this M to be stored for each iteration of i, without overwriting anything.
Files_list = getAllFiles('C:\Stellaris Measurements\Stellaris-LM4F120_all');
for i = 1:15000
B=num2str(cell2mat(Files_list(i)));
fid = fopen(B,'rb');
T= fread(fid,inf,'uint8','ieee-be');
total = numel(T);
%M=textread('C:\Users\admin\Workspace\STELLARIS-LM4F120_00_210214_104000_0001_temp_025.bin','%2c');
%M=dec2bin(M);
M= de2bi(T,8,'left-msb');
M = measure(i);
end
So, basically I want to create a martix for each of the measurement, which will store the converted binary results in a 32768*8 array.
Thanks!
BR,
\Kashif
I have the following piece of code:
for query = queryFiles
queryImage = imread(strcat('Queries/', query));
queryImage = im2single(rgb2gray(queryImage));
[qf,qd] = vl_covdet(queryImage, opts{:}) ;
for databaseEntry = databaseFiles
entryImage = imread(databaseEntry.name);
entryImage = im2single(rgb2gray(entryImage));
[df,dd] = vl_covdet(entryImage, opts{:}) ;
[matches, H] = matchFeatures(qf,qf,df,dd) ;
result = [result; query, databaseEntry, length(matches)];
end
end
It is my understanding that it should work as a Java/C++ for(query:queryFiles), however the query appears to be a copy of the queryFiles. How do I iterate through this vector normally?
I managed to sort the problem out. It was mainly to my MATLAB ignorance. I wasn't aware of cell arrays and that's the reason I had this problem. That and the required transposition.
From your code it appears that queryFiles is a numeric vector. Maybe it's a column vector? In that case you should convert it into a row:
for query = queryFiles.'
This is because the for loop in Matlab picks a column at each iteration. If your vector is a single column, it picks the whole vector in just one iteration.
In MATLAB, the for construct expects a row vector as input:
for ii = 1:5
will work (loops 5 times with ii = 1, 2, ...)
x = 1:5;
for ii = x
works the same way
However, when you have something other than a row vector, you would simply get a copy (or a column of data at a time).
To help you better, you need to tell us what the data type of queryFiles is. I am guessing it might be a cell array of strings since you are concatenating with a file path (look at fullfile function for the "right" way to do this). If so, then a "safe" approach is:
for ii = 1:numel(queryFiles)
query = queryFiles{ii}; % or queryFiles(ii)
It is often helpful to know what loop number you are in, and in this case ii provides that count for you. This approach is robust even when you don't know ahead of time what the shape of queryFiles is.
Here is how you can loop over all elements in queryFiles, this works for scalars, row vectors, column vectors and even high dimensional matrices:
for query = queryFiles(:)'
% Do stuff
end
Is queryFiles a cell array? The safest way to do this is to use an index:
for i = 1:numel(queryFiles)
query = queryFiles{i};
...
end
I am using NCSOStools for non-commutative computation in MATLAB. I create a matrix that I want to export and save to an Excel file. Here is my code:
clear all
clc
syms x
NCvars x
A=[x 2x 3x]
Normally I would be able to use the command xlswrite(filename,A) and save the matrix A to an excel file, but instead I am getting the error:
Input data must be a numeric, cell, or logical array.
Is there a simply way to save the NCpoly matrix A to Excel? I do not know if in general it is possible to change the data type to conform with the xlswrite command. Thanks very much.
I tried to save array of chars and it worked:
a = ['a', ' ','b']
xlswrite (test.xls, a)
may be, xlswrite does not support symbolic variables.
Your matrix A is symbolic, because this is how you defined x. You need to assign a definite value for A before passing it to xlswrite. This can be achieved either by substituting x with a concrete value using subs, or not defining A as symbolic in the first place.
As a workaround, you could use char to convert the symbolic expressions to a string as follows:
C = cell(size(A));
for k = 1:numel(A)
C{k} = char(A(k));
end
For an input of A = [x, 2 * x, 3 * x] you should get C = {'x', '2*x', '3*x'}. If you want to remove the asterisks (*), you could use strrep:
C = strrep(C, '*', '');
You can then pass the cell array of strings C to xlswrite.