How to append data or values to an existing .csv file??

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Manoj Murali 2012-2-10

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/28667-how-to-append-data-or-values-to-an-existing-csv-file

评论： YU Xinbo 2018-6-13

采纳的回答： Wayne King

hi..suppose i have a .csv file named csvfile.csv.And it has the values as follows:

23 45

69 84

48 78

12 34

so it has two colums.Now wat i need to do is to add values staring from the 3rd colum with out deleting the values in the 1st and 2nd colums..How can i do this...??Any one plz help..!!

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Answer 1

Wayne King 2012-2-10

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https://ww2.mathworks.cn/matlabcentral/answers/28667-how-to-append-data-or-values-to-an-existing-csv-file#answer_36985

在 MATLAB Online 中打开

Use dlmwrite with 'delimiter', ',' and '-append'

M = randn(4,4);
dlmwrite('test.csv',M,'delimiter',',');
N = randn(4,4);
dlmwrite('test.csv',N,'delimiter',',','-append');

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Manoj Murali 2012-2-10

Thanx for the reply sir..but ther is a problem here...i want the values to be appended side by side..but ur code is printing it below the already present values.I want the newly appended data to be pasted in the right side of the already present data..not below it..Can u modify ur code and tell me plzz..??

khalid malik 2015-5-2

Yes it works but it just append the data at next cell, Now if we want to append the data at desired line or col then what we need to amend in above script. I want a=[1 2 3; 4 5 6] and b=[0 9 8; 7 6 5] I want to create csv file in which b values append in file a from line 2 and col 4 Thanks

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Answer 2

William 2012-2-10

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在 MATLAB Online 中打开

Worst case you could read the current file you have

csvread(....);

Import the vectors, do you manipulation and then use

csvwrite(...)

to write it all back to a specified excel file.

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khalid malik 2015-5-5

how to append data in different col. rather than in rows? I have data in col. wise and want to append all together.

Rubedo 2017-12-20

编辑：Rubedo 2017-12-20

This may possibly help, since csvwrite uses matrices you should configure your data as so. Assigned first column to 'a', second to 'b' and new data as 'c'.

csvwrite('test.csv', [a b c]);

This should output your data as:

23 45 1

69 84 2

48 78 3

12 34 4

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Answer 3

Manoj Murali 2012-2-10

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https://ww2.mathworks.cn/matlabcentral/answers/28667-how-to-append-data-or-values-to-an-existing-csv-file#answer_36997

using dlmwrite with an '-append' is only appending the new values below the already present values.But wat i want is to append the values to the right side of the already present values..Any one plzz answer..??

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Mahmoud abouamer 2018-4-4

You can try something like dlmwrite('test.csv',M,'-append',... 'roffset',10,'coffset',11); where 10 and 11 are the rows and columns of the cell you r interested in.

YU Xinbo 2018-6-13

This method also doesn't work. The row offset is not exact the location where I want to insert. It will skip the existing rows where there is data... The problem is that I have huge data need to export to a csv... a 7*60000 matrix

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