How to import .csv files, keeping all the headers (which are on multiples rows) in order to extract some information from the headers?

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Pietro Tassan 2022-2-24

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https://ww2.mathworks.cn/matlabcentral/answers/1657985-how-to-import-csv-files-keeping-all-the-headers-which-are-on-multiples-rows-in-order-to-extract

评论： Scott MacKenzie 2022-2-25

采纳的回答： Scott MacKenzie

end_cavity1_v5_Z_-2.0000_2Power_0.0150_Spectrum.csv

Hi!

I have a bunch of .csv files that I have to manipulate and some information that I need is stored in the headers.

Such files are organized in this way:

from row 1 to row 21, organized in just one column, there are headers (strings) containing some information I need (regarding the experiments I have done);
row 22 contains the proper headers in two columns;
from row 23 to 1361 there are the values (numbers) related to the headers in row 22.

I leave here attached one of those files that I would like to analyse.

So I need to access to the values in row 7 and row 15, which are both constant for each file. For example, in the case of the file attached, the values are respectively "# CenterZ = -7923.190" and "# Power2 = 1.161346e-06". Then, I have to store from row 7 the number -7923.190 and for row 15 the number 1.161346e-06. Those values change from .csv to csv.

Do you have any idea on how I could proceed? I have checked the community posts with no success...

Hope I have been cleared in the explanation.

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Answer 1

Scott MacKenzie 2022-2-24

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1657985-how-to-import-csv-files-keeping-all-the-headers-which-are-on-multiples-rows-in-order-to-extract#answer_904025

编辑：Scott MacKenzie 2022-2-24

在 MATLAB Online 中打开

Assuming your files are consistently formatted, here's one way to extract the data values in the header lines and then read the data after the header lines into a matrix:

f = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/906250/end_cavity1_v5_Z_-2.0000_2Power_0.0150_Spectrum.csv';
C = readcell(f, 'range', '1:21');
C7 = C{7};
CenterZ = str2double(C7(13:end))
CenterZ = -7.9232e+03
C15 = C{15};
Power2 = str2double(C15(13:end))
Power2 = 1.6135e-07
M = readmatrix(f); % extract the data starting after the header lines

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Pietro Tassan 2022-2-25

Wow that works perfectly! Thank you very much for your help!

Scott MacKenzie 2022-2-25

在 MATLAB Online 中打开

@Pietro Tassan You're welcome. Glad to help.

BTW, below is another way to extract values from the header lines. This method is a bit cleaner, I think:

s = split(C(7));
CenterZ = str2double(s(4))
s = split(C(15));
Power2 = str2double(s(4))

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How to import .csv files, keeping all the headers (which are on multiples rows) in order to extract some information from the headers?

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