Splitting data array into sub arrays

Question

Ozgur 2011-9-14

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https://ww2.mathworks.cn/matlabcentral/answers/15810-splitting-data-array-into-sub-arrays

评论： Saurabh Bedi 2020-12-5

采纳的回答： Jan

Hi everyone,

I have a acquired data of 10 sec with 30720 Hz sampling freq, which results 307200 data points.

I want to split this data array into 10 sub arrays and process it seperately and use it after.

I can do it step by step using classical array manipulations but I have 8 of these data sets and splitting those causes 80 steps to manage it.

Is it possible to do that with a for or a while loop at one action? I didn't think of a algorithm about that yet. Any suggestions would be helpful.

Regards,

OZGUR

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Answer 1

Jan 2011-9-14

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https://ww2.mathworks.cn/matlabcentral/answers/15810-splitting-data-array-into-sub-arrays#answer_21427

在 MATLAB Online 中打开

The creationm of sub-arrays is inefficient. It would be better to use a 2D array:

x = rand(1, 307200);
y = reshape(x, 30720, 10);

Then the i.th part is y(:, i), which is fast and simple.

If you really want to get different arrays, use a cell:

C = num2cell(reshape(x, 30720, 10), 1);

Then C{1}, C{2}, ... are your vectors.

Do not create different variables C1, C2, ... !

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Nimrod 2016-9-15

Hey Jan but what if your x size is not even

Saurabh Bedi 2020-12-5

Hey Jan,

I have a similar issue where I am trying to reshape an array in order to form sub-arrays for a very large array. Is there a way to reshape an array containing non-integer values? For example:- i have a large array of approx. 200,000 points with values like -124.3569. How can I reshape this array?

Actually I want to split this array into sub-arrays Or cells.

I used the following code to reshape and split:-

time_avg_len = [1, 10, 30];

for i = time_avg_len(1,1:end)

if i == time_avg_len(1,3)

number_bins = ceil(max(tau/i));

disp(number_bins)

s = length(angle_array_hr);

disp(s)

angle_array_hr_reshape = reshape(angle_array_hr, (s/number_bins), number_bins);

%C = num2cell(angle_array_hr_reshape,1);

%disp(error_signal_split_list)

end

Surprisingly, If I choose i==30, the code works and I am able to reshape and split the array into 2 sub-arrays OR cells. But If I choose i==10 OR 1, It gives an error: "Error using reshape. Size arguments must be real integers." Please let me know why this happens. Is it because my array has non-integer values? but then it should not work for i==30 as well.

Anyone, Kindly help me with this.

Thanks in advance.

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Answer 2

Ozgur 2011-9-17

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https://ww2.mathworks.cn/matlabcentral/answers/15810-splitting-data-array-into-sub-arrays#answer_21713

Another question, if I want to put the subarrays into cell manually, how can I do that? (By not using "cell" function)

I've tried several for loop actions, but I couldn't manage it.

OZGUR

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Answer 3

Gokturk 2012-12-18

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https://ww2.mathworks.cn/matlabcentral/answers/15810-splitting-data-array-into-sub-arrays#answer_68799

Hi, I want to add a question related to this. How can we split data into sub arrays based on dates? Lets say we do have thousands data points for diff dates totaling a million rows in xls. I want to split this data into arrays based on the dates as the number of observations is changing from date to date. Many thnks for the help