I have a Cell Array 1*42 .
I want to save this cell array into 311029*42 array size in .mat file.enter image description here
How to do it ?
You can use cell2mat function to do this. You can see the mechanism of this function in this link (see the following image).
You can just horizontally concatenate a comma-separated list generated from the cell array, then save your new variable like so:
newData = [data{:}];
svae('your_file.mat', 'newData');
Let C be a cell array of 1x42 size. Then, run the following code to get the output array Y.
N = length(C);
L = size(C{1});
Y = size(L(1),L(2)*N);
for n = 1:N
Y(:,1+(n-1)*L(2):n*L(2)) = C{n};
end
Related
I have multiple images in a folder, and for each image, I want to store the data(pixel values) as a row vector. After I store them in a row vector I can combine these row vectors as one multi dimensional array. e.g. the data for the first image will be stored in row 1, the data for the second image will be stored in row 2 and so on. And any time I want to access a particular image data, let us say I want the third image, I can do something like this race(3,:).
I am currently getting the error:
Dimensions of matrices being concatenated are not consistent.
The error occurs here race = [race; imagevec] I am lost in how to correct this, unless imagevec = I(:)' is not converting the matrix to a row vector .
race = []; % to store all row vector
imagevec = []; % to store row vector
path = 'C:\Users\User_\somedir\'; % directory
pathfile = dir('C:\Users\User_\somedir\*.jpg'); % image file extension in directory
for i = 1 : length(path)
filename = strcat(path,pathfile(i).name); % get the file
I = imread(filename); % read file
imagevec = I(:)'; % convert image data to row vector
race = [race; imagevec]; % store row vector in matrix
end
Using a cell array instead of a matrix will allow you to index in this way even if your images are of different sizes.
You don't even have to turn them into a row vector to store them all in the same structure. You can do something like this:
path = 'C:\Users\User_\somedir\'; % directory
pathfile = dir([path,*.jpg']); % image file extension in directory
race = cell(length(pathfile),1);
for i = 1 : length(pathfile)
filename = strcat(path,pathfile(i).name); % get the file
I = imread(filename); % read file
race{i} = I; % store in cell array
end
Then when you want to perform some operation, you can simply index into the cell array. You could even turn it into a row vector, if you wanted to, as follows.
thisImage = race{3}(:)';
If you are using a matrix to store the results, all rows of a matrix must be the same length.
Cell arrays are similar to arrays except the elements need not be the same type / size.
You can accomplish what you are looking for using a cell array. First, initialize race to:
race = {};
Then try:
race = {race{:}, imagevec};
rate_arr_cst_1 = #(t) 2*sin(t)+10;
rate_arr_cst_2 = #(t) 3*sin(2*t)+8;
rate_arr_cst_h = {rate_arr_cst_1, rate_arr_cst_2};
I defined a cell array in such way and try to access in the following way:
i=1;
h = rate_arr_cst_h(i);
but what I get here is still a cell array, meaning i can't use h to evaluate t=0.1.
Your help is much appreciated!
When you do h = rate_arr_cst_h(i);, you are accessing the i^th element of the cell array, which is still a cell. If you want to access the contents of i^th cell in the cell array, you need to do: h = rate_arr_cst_h{i};. Note the use of curly brackets.
Either use a for loop:
for ii = 1:numel(rate_arr_cst_h)
hh(ii) = rate_arr_cst_h{ii}(i);
end
or you can use cellfun:
hh = cellfun(#(f) f(i), rate_arr_cst_h);
I've got a result from a web service and MatLab gladly notifies that it is a 1x1 struct. However, when I try to display it (by typing receivedData and pressing enter) I get to see this:
ResponseData: [5x1 struct]
Equally gladly, I entered the following, in my attempt to get the data viewed to me:
struct2array(responseData)
I get only a bunch (not five, more than five) of strings that might be names headers of columns of the data provided.
How do I get all the data from such structure?
You may use fieldnames to get the data from the struct and then iteratively display the data using getfield function. For example:
structvariable = struct('a',123,'b',456,'c',789);
dataout = zeros(1,length(structvariable)) % Preallocating data for structure
field = fieldnames(a);
for i = 1:length(structvariable)
getfield(structvariable,field{i})
end
Remember, getfield gives data in form of cell, not matrix.
or you can use cellfun function:
% STRUCT - your structure
% tmp_nam - structure field names
% tmp_val - values for structure field names
tmp_nam = fieldnames(STRUCT);
tmp_val = cellfun(#(x)(STRUCT.(x)),tmp_nam,'UniformOutput',false);
In order to display all elements and subelements of a structure there is a custom function that you can download here:
http://www.mathworks.com/matlabcentral/fileexchange/13831-structure-display
Some useful access syntax:
someVar = ResponseData(1) %Displays the first element
someVar = ResponseData(4) %Displays the 4th element
To display them all, one after the next
for ix = 1:length(ResponseData)
tmp = ResponseData(ix);
end
To get all the fieldnames
names = fieldnames(ResponseData)
To get all 5 data elements from the structure with the first field names, and put them into a cell array
ixFieldName = 1;
someCellArray = { ResponseData.(ixFieldName{1}) }
A small correction to Sahinsu's answer:
structvariable = struct('a',123,'b',456,'c',789);
dataout = zeros(1,length(structvariable)) % Preallocating data for structure
field = fieldnames(structvariable);
for i = 1:length(field)
getfield(structvariable,field{i})
end
I read one by one images from a directory and I wish to create an array of images with that to pass to my mexFunction that processes these images. What I am tried so far is not working. Let say I have 100 images 256x256 when I do
directory = uigetdir; fileList = dir(directory); imageVolume= [];
for idx = 3:numel(fileList)
tempImage = imread(fullfile(directory, fileList(idx).name));
imageVolume= [imageVolume tempImage];
end
Whenever I do that, I don't get an array of 256x256xn, instead I just get an image of 256x(256*n), which is not what I want. Any idea?
Use Cell Arrays. Assuming the rest of your code is right:
for idx = 3:numel(fileList)
tempImage{idx} = imread(fullfile(directory, fileList(idx).name));
end
Using cell arrays as #bjornsen suggested works. If you would rather not use cell arrays, you can use 3 dimensional matrices:
imageVolume(:,:,idx) = tempImage;
You must be sure, though, that all images are the same size. Otherwise, you're better off using cell arrays.
Right now I am creating mapstructs in Matlab and then exporting them individually as shape files using the shapewrite() function.
However, instead of exporting them individually I want to store all of them into an array and then save it at the end as one single shapefile which holds all of the points from the mapstructs stored in the array.
My problem is I don't know how to initialize an array to hold these mapstructs. I've tried
`a = struct(sizeofarray)`
but it isn't compatible with mapstructs. I would appreciate any help!
You can store any kind of data in a cell array:
a = cell(sizeofarray,1);
You can then assign them like this:
a{1} = firstmapstruct;
a{2} = secondmapstruct;
However, if I understand you correctly you have mapstructs from the MATLAB Mapping Toolbox and want to concat structs of this form:
firstmapstruct =
609x1 struct array with fields:
Geometry
BoundingBox
X
Y
STREETNAME
RT_NUMBER
CLASS
ADMIN_TYPE
LENGTH
So you should probably do
a = firstmapstruct;
a(end+1:end+numel(secondmapstruct))= secondmapstruct;
and so on...
If all of your individual mapstructs have the same fields, you should be able to initialize a structure array by replicating one of your mapstructs using the function REPMAT:
a = repmat(mapstruct1,1,N); %# A 1-by-N structure array
Then just fill in each element as needed:
a(2) = mapstruct2; %# Assign another mapstruct to the second array element
a(3).X = ...; %# Assign a value to the X field of the third element
a(3).Y = ...; %# Assign a value to the Y field of the third element
You can find out more information about Geographic Data Structures in this documentation.