I have a 4554 x 1 vector of type double, called company_info,ind_vec. I also have a another 25 x 1 vector which is of type cell array called groups.industy_labels.
groups.industy_labels contains a list of codes which are numeric.
company_info,ind_vec contains the same numeric codes.
I was planning on doing the below, where I use ismember to return the indices for each numeric code in groups.industy_labels and then do a sum on another vector which is realted to company_info,ind_vec, i.e. another 4554 x 1 vector.
[~, index_sub] = ismember(company_info.ind_vec, groups.industy_labels);
groups.industy_exps(:, 1) = accumarray(index_sub, pwgt , [], #sum, 0);
However Matlab is telling me that ismember only takes cell arrays of string. Is there another way of doing this?
Actually the error message is a bit deceptive as you can use ismember for numeric values:
x=[1 3]
y=[1 2]
ismember(x,y) %This will work
You can also use it for cell arrays, but only for strings:
x=[{'a'},{'c'}]
y=[{'a'},{'b'}]
ismember(x,y) %This will work
x=[{1},{3}]
y=[{1},{2}]
ismember(x,y) %This will fail
So in your case, you would want to use it on 2 numeric vectors, rather than 1 numeric vector and 1 cell array:
x=[1,2] %Numeric vector
y=[{1},{2}] %Cell array
y_numeric = [y{:}] %Made into a numeric vector
ismember(x,y_numeric) %This will work
Note that this assumes that each entry in the cell array only contains a number.
Related
I have a m-by-1 matrix, A. I want to find out which elements are duplicates and get their row values. (Just the row values because the matrix is m-by-1.)
I've tried
k = find(~unique(A));
but k contains the wrong values.
Here's an example of what I'm trying to do. Consider the array A;
A = [4
5
5
5
7
8
4];
Since 4 and 5 are the repeated elements here, I would like to get the row values of these elements and put them in a new array. The resulting array would be
RowValues= [1
2
3
4
7];
Note: The above is just an example and the actual array I am dealing with contains rational numbers of the type -0.0038, 1.3438 and so on in the array A.
Here is a solution using intersect:
s = sort(A);
c = intersect(s(1:2:end),s(2:2:end));
RowValues = find(ismember(A,c));
I have compared this method with the method proposed by #SardarUsama with a large [1 x 10000000] input in Octave. Here is the result:
=======INTERSECT==========
Elapsed time is 1.94979 seconds.
=======ACCUMARRAY==========
Elapsed time is 2.5205 seconds.
Find the count of each element of A using unique and accumarray, filter out the non-repeating values, use ismember to get the logical indices of repeating values and then use find to convert them to linear indices.
[C, ~, ic] = unique(A);
RowValues = find(ismember(A, C(accumarray(ic,1)>1)));
Why you get the wrong indices with your code?
Applying logical NOT on the vector of unique values would convert them to a logical vector containing true at the index where unique value is zero and false where it is non-zero and hence finding the non-zero (false in this case) elements of such a vector would lead nowhere.
I'm writing a MATLAB function to read out data into an n-dimensional array (variable dimension size). I need to be able to access a specific point in the Matrix (to write to it or read it, for example), but I don't know ahead of time how many indexes to specify.
Currently I have a current_point vector which I iterate through to specify each index, and a max_points vector which specifies the size of the array. So, if for example I wanted a 3-dimensional array of size 1000-by-15-by-3, max_points = [1000 15 3], and current_point iterates from [1, 1, 1] to [1000, 15, 3] ([1, 1, 1] -> [1000, 1, 1] -> [1, 2, 1] -> [1000, 2, 1] ->...). What I'd like to be able to do is feed current_point as an index to the matrix like so:
output_matrix(current_point) = val
But apparently something like output_matrix([1 2 3]) = val will just set outputmatrix(1:3) = 30. I can't just use dummy variables because sometimes the matrix will need 3 indexes, other times 4, other times 2, etc, so a vector of variable length is really what I need here. Is there a simple way to use a vector as the points in an index?
Using the function sub2ind to create a linear index is the typical solution to this problem, as shown in this closely-related question. You could also compute a linear index yourself instead of calling sub2ind.
However, your case may be simpler than those in the other questions I linked to. If you're only ever indexing a single point with your current_point vector (i.e. it's just an n-element vector of subscripts into your n-dimensional matrix), then you can use a simple solution where you convert current_point to a cell array of subscripts using the function num2cell and use it to create a comma-separated list of indices. For example:
current_point = [1 2 3 ...]; % A 1-by-n array of subscripts
subCell = num2cell(current_point); % A 1-by-n cell array of subscripts
output_matrix(subCell{:}) = val; % Update the matrix point
The operation subCell{:} creates the equivalent of typing subCell{1}, subCell{2}, ..., which is the equivalent of typing current_point(1), current_point(2), ....
I know it is too late but for anybody who will find this topic. the easiest way that work for me is to use: diag(A (x(:),y(:)) );
unfortunately this works only if you need to get values from the matrix, not for changing values
You can use the sub2ind function to get the linear index from the subscript.
Example:
A=magic(4)
A =
16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1
selectElement={2,3}; %# get the element at position 2,3 in A.
indx=sub2ind(size(A),selectElement{:});
A(indx)
ans =
10
In the above example, I've stored the subscripts (can be any number of dimensions) as a cell. If you have it stored as a vector, simply use num2cell() to convert it to a cell.
You can now easily assign a value to this as A(indx)=value;. I've used different variables than yours to keep the answer general, but the idea is the same and you just need to replace the variable names.
You also mentioned in your post that you're looping from (1,1,1) till some value, (1000,15,3) and assigning a value to each of these points. If you're looping along the columns, you can replace this entire operation with a vectorized solution.
Let finalElement={1000,15,3} be the final step of the loop. As before, find the linear index as
index=sub2ind(size(A),finalElement{:});
Now if you have the values you assign in the loop stored as a single vector, values, you can simply assign it in a single step as
A(1:index)=values;
I am using two cells for storing the targeted and the expected value of a neural network process in matlab. I have used two 1*1 cell array for storing the values respectively. And here is my code.
cinfo=cell(1,2)
cinfo(1,1)=iter(1,10)%value is retrieved from a dataset iter
cinfo(1,2)=iter(1,11)
amp1=cinfo(1,1);
amp2=cinfo(1,2);
if amp1 == amp2
message=sprintf('NOT DETECTED BY THE DISEASE');
uiwait(msgbox(message));
But when i run the above code, the get the following error :
??? Undefined function or method 'eq' for input arguments of type 'cell'.
Error in ==> comparison at line 38
if amp1 == amp2
How to solve this problem?
The problem is how you indexed things. A 1x1 cell array does not make a lot of sense, instead get the actual element in the single cell, by indexing with curly brackets:
amp1=cinfo{1,1}; # get the actual element from the cell array, and not just a
amp2=cinfo{1,2}; # 1x1 cell array by indexing with {}
if (amp1 == amp2)
## etc...
However, note that if amp1 and amp2 are not scalars the above will act weird. Instead, do
if (all (amp1 == amp2))
## etc...
Use isequal. That will work even if the cell's contents have different sizes.
Example:
cinfo=cell(1,2);
cinfo(1,1) = {1:10}; %// store vector of 10 numbers in cell 1
cinfo(1,2) = {1:20}; %// store vector of 20 numbers in cell 2
amp1 = cinfo(1,1); %// single cell containing a length-10 numeric vector
amp2 = cinfo(1,2); %// single cell containing a length-20 numeric vector
if isequal(amp1,amp2)
%// ...
In this example, which parallels your code, amp1 and amp2 are cell arrays consisting of a single cell which contains a numeric vector. Another possibility is to directly store each cell's contents into amp1, amp2, and then compare them:
amp1 = cinfo{1,1}; %// length-10 numeric vector
amp2 = cinfo{1,2}; %// length-20 numeric vector
if isequal(amp1,amp2)
%// ...
Note that even in this case, the comparisons amp1==amp1 or all(amp1==amp2) would give an error, because the vectors have different sizes.
I have a 1xN cell, call it X, whose components X{i} (for i in {1, 2, ..., N}) are either Mx1 cells of strings or Mx1 numeric vectors.
NOTE: the fact that X contains both text cells and numeric vectors precludes using cell2mat here:
>> tmp = cell2mat(X);
Error using cell2mat (line 46)
All contents of the input cell array must be of the same data type.
My question is:
What's MATLAB's "idiomatic" way to transpose this data into an array of M 1xN cells?
EDIT: To be clear, the data structure I want to arrive at, let's call it Y, is an M-long array of 1xN cells (each consisting of a mixture of numbers and strings). E.g., if N=2, and if X{1} is an Mx1 cell of strings, and X{2} is an Mx1 vector of doubles, then the desired data structure Y is such that, for any 1 ≤ i ≤ M, Y(i,:) is a 1x2 cell whose first element is the i-th string in X{1} and whose second element is the i-th double in X{2}. I.e. Y(i,:) would be the same as the 1x2 cell Yi defined as follows
xi1 = X(i, 1);
xi2 = X(i, 2);
Yi = {xi1{1} xi2{1}};
(Sorry for the awkwardness! I just can't find a MATLAB expression for Yi directly in terms X and i, without having to create intermediate variables xi1 and xi2.)
First of all, to my knowledge there is no 'idiomatic' way of doing that i Matlab. Remember, we're talking about a complex data structure with nested cells and differing types.
I tried to cook up a solution based on cellfun. It quickly got complicated and I didn't even succeed. So instead I would recommend doing a simple double for loop and a if like this:
for a=1:size(X,2),
for b=1:size(X{a},1),
if iscell(X{a}),
Y{a,b} = X{a}{b};
else
Y{a,b} = X{a}(b);
end
end
end
If X = {{'s1';'s2'} [3; 4]} then this solution will give Y = {'s1' 3 ;'s2' 4}.
As you see I have flattened the cell to one depth. To get your 1xN vectors, do Y{1,:}
Hope it helps
If each cell in X contains a vector of the same size convert it to a matrix, transpose that matrix and then convert it back to a cell array?
tmp = cell2mat(X);
Y = mat2cell(tmp', ...);
Here is the function:
feval(#(y) feval(#(x) cellfun(#(varargin)[varargin],x{:},'un',0), cellfun(#(x) feval(#(varargin) varargin{3-varargin{1}}(), iscell(x),x,num2cell(x)),y,'un',0)), {{'1','2','3'},[4 5 6],{7,8,9}})
Or stored as a function name:
transpose_nest = #(cell_nest) feval(#(y) feval(#(x) cellfun(#(varargin)[varargin],x{:},'un',0), cellfun(#(x) feval(#(varargin) varargin{3-varargin{1}}(),iscell(x),x,num2cell(x)),y,'un',0)), cell_nest);
transpose_nest({{'1','2','3'},[4 5 6],{7,8,9}})
{{'1',4,7},{'2',5,8},{'3',6,9}}
It is based on a Matlab equivalent of Scheme's (apply map list '(("1" "2" "3") (4 5 6) (7 8 9))) that only works on sub cells:
feval(#(x) cellfun(#(varargin)[varargin],x{:},'un',0), {{'1','2','3'},{4,5,6},{7,8,9}})
{{'1',4,7},{'2',5,8},{'3',6,9}}
The extra part:
#(x) feval(#(varargin) varargin{3-varargin{1}}(), iscell(x), x, num2cell(x))
is an if statement within an anonymous function that calls num2cell if any sub element is a vector
I'm writing a MATLAB function to read out data into an n-dimensional array (variable dimension size). I need to be able to access a specific point in the Matrix (to write to it or read it, for example), but I don't know ahead of time how many indexes to specify.
Currently I have a current_point vector which I iterate through to specify each index, and a max_points vector which specifies the size of the array. So, if for example I wanted a 3-dimensional array of size 1000-by-15-by-3, max_points = [1000 15 3], and current_point iterates from [1, 1, 1] to [1000, 15, 3] ([1, 1, 1] -> [1000, 1, 1] -> [1, 2, 1] -> [1000, 2, 1] ->...). What I'd like to be able to do is feed current_point as an index to the matrix like so:
output_matrix(current_point) = val
But apparently something like output_matrix([1 2 3]) = val will just set outputmatrix(1:3) = 30. I can't just use dummy variables because sometimes the matrix will need 3 indexes, other times 4, other times 2, etc, so a vector of variable length is really what I need here. Is there a simple way to use a vector as the points in an index?
Using the function sub2ind to create a linear index is the typical solution to this problem, as shown in this closely-related question. You could also compute a linear index yourself instead of calling sub2ind.
However, your case may be simpler than those in the other questions I linked to. If you're only ever indexing a single point with your current_point vector (i.e. it's just an n-element vector of subscripts into your n-dimensional matrix), then you can use a simple solution where you convert current_point to a cell array of subscripts using the function num2cell and use it to create a comma-separated list of indices. For example:
current_point = [1 2 3 ...]; % A 1-by-n array of subscripts
subCell = num2cell(current_point); % A 1-by-n cell array of subscripts
output_matrix(subCell{:}) = val; % Update the matrix point
The operation subCell{:} creates the equivalent of typing subCell{1}, subCell{2}, ..., which is the equivalent of typing current_point(1), current_point(2), ....
I know it is too late but for anybody who will find this topic. the easiest way that work for me is to use: diag(A (x(:),y(:)) );
unfortunately this works only if you need to get values from the matrix, not for changing values
You can use the sub2ind function to get the linear index from the subscript.
Example:
A=magic(4)
A =
16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1
selectElement={2,3}; %# get the element at position 2,3 in A.
indx=sub2ind(size(A),selectElement{:});
A(indx)
ans =
10
In the above example, I've stored the subscripts (can be any number of dimensions) as a cell. If you have it stored as a vector, simply use num2cell() to convert it to a cell.
You can now easily assign a value to this as A(indx)=value;. I've used different variables than yours to keep the answer general, but the idea is the same and you just need to replace the variable names.
You also mentioned in your post that you're looping from (1,1,1) till some value, (1000,15,3) and assigning a value to each of these points. If you're looping along the columns, you can replace this entire operation with a vectorized solution.
Let finalElement={1000,15,3} be the final step of the loop. As before, find the linear index as
index=sub2ind(size(A),finalElement{:});
Now if you have the values you assign in the loop stored as a single vector, values, you can simply assign it in a single step as
A(1:index)=values;