Compile mulitple csv files into one large table

Question

ANNE NDJALI 2019-3-8

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评论： dpb 2019-3-9

I have 90 csv files, each with 5 columns of data.

I need to read all 90 csv files into one large excel table, which pulls an additional 2 blank columns from each csv file (total of 7*90 columns wide).

I have tried this code, which does not yet include anything for adding the extra 2 columns, and have been unsucessful in pulling data together. It pulls data from one of the csv files only and pulls the data in on different rows.

% Read in data from Excel
source_dir = 'directory_name';
source_files = dir(fullfile(source_dir,'*.csv'))
% Import Data
for i = 1:length(source_files)
    Data = xlsread(fullfile(source_dir, source_files(i).name))  
end
xlswrite('file_i_want',Data,'tab_name')

Thank you for your help

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Answer 1

dpb 2019-3-9

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编辑：dpb 2019-3-9

在 MATLAB Online 中打开

You're overwiting Data every iteration...

source_dir = 'directory_name';
source_files = dir(fullfile(source_dir,'*.csv'));
Data=[];
for i = 1:length(source_files)
  Data=[Data; xlsread(fullfile(source_dir, source_files(i).name))];
end
xlswrite('file_i_want',Data,'tab_name')

The above will work presuming all the data in the files is numeric. xlsread is overhead-intensive, however, for ordinary text files. I'd do something like

Data=[Data; importdata(fullfile(source_dir, source_files(i).name))];

instead, probably. Adding columns is essentially trivial although I'd ask what's the point in having more columns than useful data until you have something to put there?

Data=[Data zeros(size(Data,1),2)];

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ANNE NDJALI 2019-3-9

Thank you!

And, yes. I will use those two blank columns to have space to process the 5 columns of raw data.

dpb 2019-3-9

But those columns can be created dynamically by simple assignment of the result of the previous computations--you don't need to create empty space.

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Answer 2

Walter Roberson 2019-3-9

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% Read in data from Excel
source_dir = 'directory_name';
source_files = dir(fullfile(source_dir,'*.csv'))
numfiles = length(source_files);
Data = cell(1, numfiles);
% Import Data
for i = 1:numfiles
    thisdata = xlsread(fullfile(source_dir, source_files(i).name));
    thisdata(:,6:7) = 0;    %or whatever is appropriate
    Data{1,i} = thisdata;
end
Data = [Data{:}]; %create one big numeric matrix    
xlswrite('file_i_want',Data,'tab_name')