Extracting Data from Cells

Asked by Devrim Tugberk on 19 Jul 2019

Latest activity Commented on by madhan ravi on 19 Jul 2019

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Dear Matlab users,

I am facing some trouble extracting data from a cell. I attached the a screenshots showing what my cell looks like (cells within a cell). Each cell in the "big" cell has xyz data and i would like to extract each column representing the respective coordinates as column vectors.

My explanation might have been confusing so i will try summarize: Extract the "minor" cells from the main cell, extract the xyz from each minor cell as column vectors.

Thank you for the help

3 Comments

Guillaume on 19 Jul 2019

What does extract mean? What do you want to do afterward?

Adam Danz on 19 Jul 2019

I interpreted it as an indexing question.

Devrim Tugberk on 19 Jul 2019

My goal was the "extract" the xyz coordinates as column vectors and plot them using scatter3()

3 Answers

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Answer by madhan ravi on 19 Jul 2019

Edited by madhan ravi on 19 Jul 2019

Accepted Answer

vv=cellfun(@(x) x(:,1:3),cross_sections,'un',0); % assuming the first three columns in each cell represents x,y & z
v=cat(1,vv{:}); % gathering x,y, & z of each cell into one matrix
scatter3(v(:,1),v(:,2),v(:,3))
%         x -^      ^- y   ^- z

7 Comments

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Devrim Tugberk on 19 Jul 2019

Perfect! Thank you all very much

Devrim Tugberk on 19 Jul 2019

One last tiny tweak, is there a way I could supress the scatter3 function so it doesnt spit out 138 figures? Maybe just give me 138 tables or vectors or something which i can refer back to and plot the desired one only?

madhan ravi on 19 Jul 2019

Then for instance:

scatter3(vv{2}(:,1),vv{2}(:,2),vv{2}(:,3))

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Answer by Adam Danz on 19 Jul 2019

Edited by Adam Danz on 19 Jul 2019

I think this is the format of your data:

C = {rand(20,4),rand(15,4),rand(22,4)};

Extract the first 3 columns of cell 2

C{2}(:,1:3)

Extract column 2 of cell 3

C{3}(:,2)

Extract the entire matrix from cell 1

C{1}

Extract the entire matrix from cell 1 but reorganize it into a single column

C{1}(:)

1 Comment

Adam Danz on 19 Jul 2019

"My goal was the "extract" the xyz coordinates as column vectors and plot them using scatter3()"; " I need to have 3 column vectors for each cell"

@ Devrim Check out the 2nd block of code in my answer. It does what you're describing. If you want to perform that block on all cells,

c3 = cellfun(@(x)x(:,1:3), C, 'UniformOutput', false)

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Answer by Guillaume on 19 Jul 2019

Edited by Guillaume on 19 Jul 2019

If you want to create a scatter3 plot using the coordinates from all the cells of Cross_sections, this is how I'd go about it:

allsections = vertcat(Cross_sections{:});
scatter3(allsections(:, 1), allsections(:, 2), allsections(:, 3));

2 Comments

madhan ravi on 19 Jul 2019

Probably you meant:

allsections = vertcat(Cross_sections{:});

Guillaume on 19 Jul 2019

Indeed! Otherwise, the operation does nothing.

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Extracting Data from Cells

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