Output of cell arrays into another array

I've extracted information from 142 different files, which is stored in CSV-file with two columns, which contains both number and text. I want to copy row 11-145 of the second column, and paste it into a matrix/cell. Then, I want to skip the next 10 rows, and copy row 156-290 and paste it into the next column etc etc. I have tried the following code:

original=readcell('sample_file.csv');
overview=cell(145,135); 

for i=1
    for j=1
    overview{:,i}=original{i+10:i+144,2};
    j=j+1;
    end
    i=i+1;
    if i>20590 % this is the total number of rows in the original file
        break
    end
end

However, this gives me the following error: Assigning to 145 elements using a simple assignment statement is not supported. Consider using comma-separated list assignment.

Can somebody help me out please?

[Karim]

Hello,

Can you add the document to the question? This makes it easier to look at the data.

Best regards

[Lieke Pullen]

Unfortunately I can't, since it's medical data and thus confidential. I am sorry! But the data consists of characters and numbers.

[Stephen23]

@Lieke Pullen: a sample data file does not have to contain confidential data. It just has to have the same format and accurately represent the delimiters, end-of-lines, and values (e.g. numeric formats) found in the actual data files.

Generally descriptions of data tend to be much less accurate than sample data itself.

[Lieke Pullen]

@Stephen23 You are right, I have created a small sample file and attached it to the code.

Answer 1

[Karim]

Hello,

Here you have a bit of example code with some random data, hope it helps.

numFiles = 142;
TotalRows = 20590;
SkipRows = 10;

% create some pseduo data
SomeData = {'String 1' 1 'String 2' 2 'String 3' 3};
% assume we want some cell with at least TotalRows rows and 2 columns
original = SomeData(randi(numel(SomeData),TotalRows,2));

% generate the indices of the data we want to extract
SkipMe = 1:(TotalRows/numFiles):TotalRows;
SkipMe = repmat(SkipMe,SkipRows,1) + repmat((0:(SkipRows-1))',1,numel(SkipMe));
SkipMe = SkipMe(:);

CopyMe = true(TotalRows,1);
CopyMe(SkipMe) = false;

% now extract the data from the 2 column
overview = original(CopyMe,2);

% reshape the data so that each column represents 1 file
overview = reshape(overview,[],numFiles);

size(overview)

ans = 1×2

135 142

[Lieke Pullen]

Hi KASR, thank you for your answer, your script works! However, now the 136th row in first column is already the first row of what supposed to be the second column. Thus, they are shifted and the dimensions of the matrix actually have to be 135x142 (that is my mistake, my apologies). How do I adjust that?

[Karim]

ah yes, this is because i switched the indexes on the last row it should state:

overview = reshape(overview,[],numFiles);

to have the files as columns.

I will modify the example code above.

Answer 2

[Ayush Singh]

Hi Lieke,

From your question I understand you want to extract some portion of data from your csv file.

You could use readtable function to read your file in table format and then apply the matrix operations on the output table

To extract in table format -

table = readtable('document.csv')

And suppose to extract certain row and column then

extracted_table = table(11:145,:2)  % 11-145 row of 2nd column