MATLAB: How to index a cell array

cell arraysindex

Hallo,

I have a structure (K) with many fields, containg a field (elevation) which is (161*1 cell) array, each cell is a matrix (n*1) double.

I wanted to find all the elements in each matrix that is more than 0 then calculate the area of these values (above 0)

firstly I made a new cell array of the indexs that I needed

idx = arrayfun(@(K) K.elevation >=0, K, 'UniformOutput', false)';

now I want to use the function trapz to find the area

I tried many things, but I'm getting always errors like 'Unable to use a value of type cell as an index or 'Expected one output from a curly brace or dot indexing expression, but there were 161 results'

Can someone help me with this issue?

many thanks!

Best Answer

Try :

area_r = arrayfun(@(a) cellfun(@(c) trapz(c(c>=0)),a.elevation,'UniformOutput',false), K, 'UniformOutput',false);

I hope it helps !

Related Solutions

MATLAB: Question on cell array

K = cellfun(@(x)x(x~=0),K,'UniformOutput',false)

MATLAB: Ndgrid on cell array of vectors

What you are asking for is the cartesian product of the sets.

If your cell array only contains two sets (each with arbitrary size):

c1 = {{[1 2],[2 3]}, {[10 11], [11 12]}}
assert(numel(c1) == 2, 'only works with two sets')
[idx1, idx2] = ndgrid(1:numel(c1{1}), 1:numel(c1{2});
c2 = arrayfun(@(i1, i2) [c1{1}(i1), c1{2}(i2)], idx1(:), idx2(:), 'UniformOutput', false);
c2 = vertcat(c2{:})

A completely generic version that works with any number of sets:

c1 = {{[1 2],[2 3]}, {[10 11], [11 12]}, {4, 5, [6 7]}} %3 sets here
indices = cell(1, numel(c1));   %output variable for ndgrid
ndgridin = cellfun(@(c) 1:numel(c), c1, 'UniformOutput', false); %input arrays for ndgrid
[indices{:}] = ndgrid(ndgridin{:}); %get ngrid result
indices = cellfun(@(idx) reshape(idx, [], 1), indices, 'UniformOutput', false); %reshape ndgrid outputs into columns
catfun = @(nset, subsets) [arrayfun(@(n, i) c1{n}{i}, nset, subsets, 'UniformOutput', false)];
c2 = arrayfun(@(varargin) catfun(1:numel(c1), [varargin{:}]), indices{:}, 'UniformOutput', false);
c2 = vertcat(c2{:})

Best Answer

Related Solutions

MATLAB: Question on cell array

MATLAB: Ndgrid on cell array of vectors

Related Question