combining different csv files from a folder into one matrix

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Michel Nieuwoudt 2019-5-22

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评论： Michel Nieuwoudt 2019-5-22

Hello, I have 800 files with 1554rows and 2columns so (1554x2) , that I'd like to read from a folder and then combine them into a large matrix of 1554x801. The first column is common to each file, and so I'd like to set only the first column in the final matrix as the same column of all the files, and then the subsequent columns as the second column of each of the 800 files. I hope this makes sense.

Example:

A.csv=[1 2; 4 5] and B.csv=[1 8 ;4 7], C.csv=[1 6;4 10]

I'd like to combine these into

Combined=[1 2 8 6; 4 5 7 10]

Would anyone possibly have a code for this? I'm new to Matlab and have tried a number of codes that merge files. but they stack them horizontally so I get

[1 2;4 5;1 8;4 7;1 6;4 10].

Thank you!

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采纳的回答

Stephen23 2019-5-22

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编辑：Stephen23 2019-5-22

在 MATLAB Online 中打开

"Is theremaybe a way to list the filenames in the same order, then add them afterwards as the top row to the table?"

You could use a table:

O = {'ReadVariableNames',false};
D = '.'; % path to the directory where the files are saved.
S = dir(fullfile(D,'*.csv'));
for k = 1:numel(S)
    U = readtable(fullfile(D,S(k).name),O{:});
    [~,N] = fileparts(S(k).name);
    U.Properties.VariableNames = {'time',N};
    if k==1
        T = U;
    else
        T = join(T,U);
    end
end

Giving (the test files are attached to this answer):

>> T
T = 
    time    A    B    C 
    ____    _    _    __
    1       2    8     6
    4       5    7    10
>> T.B
ans =
     8
     7

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Michel Nieuwoudt 2019-5-22

Hi Stephen,

This is exactly what I needed. Thank you so so much!

Best wishes,

Michel

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KSSV 2019-5-22

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在 MATLAB Online 中打开

csvfiles = dir('*.csv') ; 
iwant = zeros(1554,801) ; 
for i = 1:length(csvfiles)
    data = csvread(csvfiles(i).name) ; 
    if i == 1
        iwant(:,1:2) = data ;
    else
        iwant(:,i+1) = data(:,2) ;
    end
end

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KSSV 2019-5-22

It can be but...why unnecessary complexity? You should take it as a table.

Michel Nieuwoudt 2019-5-22

I need to know the filename that each column represents. Is theremaybe a way to list the filenames in the same order, then add them afterwards as the top row to the table?

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