Pythonic way in matlab to decompose array to variables

Question

So I want to decompose array to multiple variables. For example, I have 'data' array of (136,9) size which is of double type. I want to decompose the values of data(1,:) to multiple variables something like below:

[frm_id,seq_id,xmin,ymin,w,h,temp1,temp2,temp3] = data(1,:);

In python it was straightforward, but above code gives following error in matlab:

Insufficient number of outputs from right hand side of equal sign to satisfy
assignment.

I can go with something like

frm_id = data(1,1);
seq_id = data(1,2);
%ect

But I do believe there must be matlab (more neat) way to do this operation.

Thanks!

I haven't seen anything like that in Matlab. Why is frm_id = data(1,1); seq_id = data(1,2); not OK? because it does not look neat? — Anthony
– Anthony, Commented May 1, 2017 at 1:45
Yep, I need to write data(j,index) 9 times :) . So I am looking for something more neat — Jumabek Alikhanov
– Jumabek Alikhanov, Commented May 1, 2017 at 2:15
If you want to assign each of the 9 columns to a new array, then you have to write 9 assignments. Maybe consider using another data structure so you only have to write it once? — user6645417
– user6645417, Commented May 1, 2017 at 2:17

rahnema1 · Accepted Answer · 2017-05-01 02:51:02Z

4

You can use num2cell to convert the matrix to a cell array then copy contents of the cell to each variable:

C = num2cell(data,1);
[frm_id,seq_id,xmin,ymin,w,h,temp1,temp2,temp3] = C{:};

answered May 1, 2017 at 2:51

rahnema1

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4 Comments

Anthony Over a year ago

Didn't know cell array can be used like this, which is brilliant. Just a thought through my mind. Is the underlying returned value of a function a cell type?

rahnema1 Over a year ago

@Anthony Which function? The returned value of num2cell is a cell type:)

Anthony Over a year ago

any function. I've realised my question is off-topic already.

Jumabek Alikhanov Over a year ago

@rahnema1 Brilliant, that's what I was looking for!

Anthony · Accepted Answer · 2017-05-01 02:25:45Z

1

I can only suggest you to create a function like this:

function [frm_id,seq_id,xmin,ymin,w,h,temp1,temp2,temp3] = myfunction (data)

frm_id = data(:,1);
seq_id = data(:,2);
xmin = data(:,3);
ymin = data(:,4);
w = data(:,5);
h = data(:,6);
temp1 = data(:,7);
temp2 = data(:,8);
temp3 = data(:,9);

so in your main code

[frm_id,seq_id,xmin,ymin,w,h,temp1,temp2,temp3] = myfunction(data);

answered May 1, 2017 at 2:25

Anthony

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