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

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.

Answer 1

[Scott MacKenzie]

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

[Pietro Tassan]

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

[Scott MacKenzie]

@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))