How to create an array from a 'for loop' of numeric data read from multiple excel files?

1. A list of excel files is made
2. The numeric data is imported from multiple excel files using 'xlsread' in a for loop.

>> facdata={'1.csv','2.csv','3.csv'};

>> for fn=facdata

xlsread(fn{:},'D9:D9');

end

[Stephen23]

1. Use DIR() rather than writing out a list like that.
2. Use READMATRIX rather than deprecated functions like XLSREAD.

See: https://www.mathworks.com/help/matlab/import_export/process-a-sequence-of-files.html

Answer 1

[R]

Hi @Nicholas Findanis,

Here how you can do it:

% List of Excel files
facdata = {'1.xlsx', '2.xlsx', '3.xlsx'}; % Ensure the file extension is correct

% Initialize an array to store the data
dataArray = []; % Or preallocate if you know the size

% Loop through each file and read the specified cell
for i = 1:length(facdata)
    % Read the numeric data from each file
    data = xlsread(facdata{i}, 'D9:D9');
    
    % Append the data to the array
    dataArray = [dataArray; data]; % Vertically concatenate
end

% Display the collected data
disp('Collected Data:');
disp(dataArray);

Note that xlsread is not recommended as of now. You should use readtable instead. To use readtable instead of xlsread, you'll need to adjust your approach since readtable reads entire tables rather than specific cells. However, you can still achieve the same goal by reading the table and then extracting the specific cell value you need. Here's how you can do it:

for i = 1:length(facdata)
    % Read the entire table from the Excel file
    tableData = readtable(facdata{i});
    % Extract the value from cell D9
    % Assuming D9 corresponds to the 9th row and 4th column in zero-indexed format
    data = tableData{9, 4}; % Adjust indices if the table has headers
    % Append the data to the array
    dataArray = [dataArray; data]; % Vertically concatenate
end

Hope this helps.

[Nicholas Findanis]

Thank you this information was so quick to respond and works a treat. I also found a way to concatenate CSV files using the following method.

>> facdata={'1.csv','2.csv','3.csv'};

>> for i=1:n

list(:,i)=csvread(sprintf('%d.csv',i),8,3,[8,3,8,3]);

end

Very much appreciate your help!