Importing table from text file and matching header to column

38 vues (au cours des 30 derniers jours)
Lucas Wong
Lucas Wong le 20 Mar 2022
Commenté : Lucas Wong le 21 Mar 2022
Hi everyone,
Here is an example of my data:
# r CAC-CAC CAC-OAC
0.2700000E+01 0.0000000E+00 0.0000000E+00 0.3860216E-03 0.2814651E-01
0.2730000E+01 0.0000000E+00 0.0000000E+00 0.3775852E-03 0.2753156E-01
0.2760000E+01 0.0000000E+00 0.0000000E+00 0.5541359E-02 0.1041859E+00
0.2790000E+01 0.0000000E+00 0.0000000E+00 0.7230470E-02 0.1176749E+00
0.2820000E+01 0.0000000E+00 0.0000000E+00 0.1096994E-01 0.1432550E+00
0.2850000E+01 0.0000000E+00 0.0000000E+00 0.1870899E-01 0.1847078E+00
I would like to import my data into a table, with the text in the first row used as a variable for each column that it lines up with. The unwanted "#" character and the inconsistent spacing at the start of the first row means that readtable(example_data.txt); does not does not produce the correct headers for the table and instead leads to Var1, Var2,..., ect.
For example, in Excel the import data option slices up the data and the headers end up in the correct location in the imported table:
Note that some of the columns do not have headers and I do not require this data in my imported table.
I am very new to MATLAB, so any help is very appreciated!
Cheers!

Réponse acceptée

AndresVar
AndresVar le 20 Mar 2022
Modifié(e) : AndresVar le 20 Mar 2022
The code it generated for your data did not look as pretty as it usually does, but seems to do the job.
Edit: noticed the import tool detected 'fixedwidth' filetype, but readtable seems to detect 'delimitedtext'. So you can specify fixedwidth in the options. The variablenamingrule option doesn't seem necessary but there is a warning without it.
opts = detectImportOptions('example_data.txt',FileType='fixedwidth',VariableNamingRule='preserve');
t1 = readtable("example_data.txt",opts)
t1 = 6×6 table
# r CAC-CAC Var4 CAC-OAC Var6 __________ ____ _______ ____ __________ ________ {0×0 char} 2.7 0 0 0.00038602 0.028147 {0×0 char} 2.73 0 0 0.00037759 0.027532 {0×0 char} 2.76 0 0 0.0055414 0.10419 {0×0 char} 2.79 0 0 0.0072305 0.11767 {0×0 char} 2.82 0 0 0.01097 0.14325 {0×0 char} 2.85 0 0 0.018709 0.18471
t1.("#")=[] % remove the # column
t1 = 6×5 table
r CAC-CAC Var4 CAC-OAC Var6 ____ _______ ____ __________ ________ 2.7 0 0 0.00038602 0.028147 2.73 0 0 0.00037759 0.027532 2.76 0 0 0.0055414 0.10419 2.79 0 0 0.0072305 0.11767 2.82 0 0 0.01097 0.14325 2.85 0 0 0.018709 0.18471
  6 commentaires
AndresVar
AndresVar le 20 Mar 2022
Modifié(e) : AndresVar le 20 Mar 2022
@Lucas Wong there is an extra space at the end of the first row that messes it up. BUT looks like just specificying VariableNamesLine=1 sorta solves the problem.
opts = detectImportOptions('example_data2.txt', ...
FileType='fixedwidth',VariableNamingRule='preserve', ...
VariableNamesLine=1 );
% optional: sanitize the variable names by removing white spaces and
% replacing unwanted characters.
opts.VariableNames = strtrim(strrep(strrep(opts.VariableNames,...
'-','_'), '#',''));
t1 = readtable("example_data2.txt",opts)
figure;
plot(t1.r,t1.CAC_CAC);
Lucas Wong
Lucas Wong le 21 Mar 2022
You're the man! Thanks for this.

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