How can I select items in a double list?

Hi everyone!

I have a variable which is (105 x 1 double) and I need to select from the first item to 3rd, from 4th item to 6th and from 7th item to 9th.

When, for instance, I apply:

TA8=T_C((1:3):1)

Only appears the first element and not the 2nd and 3rd ones.

How can I show the three elements?

Thank U

Answer 1

[Walter Roberson]

reshape(T_C,3,[])

Now the groups of 3 appear as columns.

[Jonathan Bijman]

Thanks, but the double list corresponds to averages of measuments of 3 groups who are the same along the time, and I need to show them in such a way that appears from 1:3, 4:6, 7:9 (similar to a for loop), because I have to graph them next.

So my idea is:

T_A8 = (1:3) in all the double list

T_C5 = (4:6) in all the double list

T_E1 = (7:9) in all the double list

So that I plot them as 3 graphs along the time.

I hope you get it.

Thanks again

[Walter Roberson]

I do not understand what you mean about "in all the double list" ? You indicated you have one variable that is 105 x 1, not several different variables.

[Jonathan Bijman]

I mean that is only one variable T_C which correspond to the average of three different samples (in triplicate each one, 9 in total). That’s why I need to associate in three groups (A8, C5 and E1)

[Walter Roberson]

BC = num2cell( reshape(T_C,3,[]), 1);
[T_A8, T_C5, T_E1, T_whatever] = deal(BC{:});

[Jonathan Bijman]

I wrote:

BC = num2cell(reshape(T_C,3,[]), 1);
[T_A8, T_C5, T_E1] = deal(BC{:});

Appears:

Error using deal (line 37)
The number of outputs should match the number of inputs.
Error in T_Ambos (line 26)
[T_A8, T_C5, T_E1] = deal(BC{:});

[Walter Roberson]

You need one output for each column.

Though I thought you were giving examples and wanted to continue for all of the groups. If you just want those specific parts then just do three assignments,

T_A8 = T_C(1:3);
T_C5 = T_C(4:6);
T_E1 = T_C(7:9);

Though seeing your response to someone else, it looks like what you want is

T_A8 = T_C(1:3:end);
T_C5 = T_C(2:3:end);
T_E1 = T_C(3:3:end);

[Jonathan Bijman]

Thank U again @Walter Roberson for your wisdom and help.

Very thankful =)

Answer 2

[Image Analyst]

Try

TA8 = T_C(1:3);

etc. Or for all of them in turn:

for k = 1 : 3 : length(T_C)  % Starting at 1, 4, 7, etc....
    TA8 = T_C(k:k+2); % Get this group of 3 elements.
    % Now do something with TA8
end

[Jonathan Bijman]

Thanks, I apply this

for k = 1 : 3 : length(T_C)  % Starting at 1, 4, 7, etc....
    TA8 = T_C(k:k+2); % Get this group of 3 elements.
    T_A8=[TA8] % I want to show as a matrix of 1 column
end

but shows only 1 column of 3 firsts items, how can I show as a matrix of 1 column with all the items?

[Jonathan Bijman]

When I apply this:

for k = 1 : 3 : length(T_C)  % Starting at 1, 4, 7, etc....
    TA8 = T_C(k:k+2); % Get this group of 3 elements.
    T_A8=[TA8,1] % Now do something with TA8
end

Appers this error:

Error using horzcat
Dimensions of arrays being concatenated are not consistent.
Error in T_Ambos (line 27)
    T_A8=[TA8,1] % Now do something with TA8

[Image Analyst]

Attach a .mat file with the paper clip icon that has your variable in it.

I guess we really don't know what you want. Do you want extractions of 3 elements at a time like you asked for, and we gave you, or do you want something else? Please show, with a numerical example of say an input vector of 12 elements, exactly what you want as the output.

[Jonathan Bijman]

I'm sorry, my english sometimes is bad =(.

I hope you get it with this image.

I want to associate all A8 (corresponds to 1, 4, 7, etc...), C5 (corresponds to 2, 5, 8, etc...) and E1 (3, 6, 9, etc...)

Thanks for your help

[Image Analyst]

Sounds like, from your comment to Walter, that you've got it all solved now, so there is no need for me to answer anymore.

[Jonathan Bijman]

Yes, but I appreciate your help @Image Analyst anyway.

Thank U =)