How do I get readtable to skip lines with certain text?

Text file for example:

2021/07/20 17:32:11> VO1=  81  VS1=  80  I1=    10.2  VO2=   0  VS2=   0  I2=     0.0
2021/07/20 17:32:11> HV ramping finished.
2021/07/20 17:33:04> VO1= 100  VS1= 100  I1=     5.0  VO2=   0  VS2=   0  I2=     0.0

How do I get readtable to skip lines with text like the line with "HV ramping finished"? I've tried using TreatAsMissing and CommentStyle but neither seemed to work.

Answer 1

[dpb]

That's not a great format for readtable to try to parse -- it's got the variable names as columms and so are interpreted as data -- and the 'TreatAsMissing' works only for numeric variables for some reason I've never fully understood/yet understand the logic behind.

It takes quite a lot of munging on the import options object, but one can make it happen -- whether it's easier that way or to just read as cellstr array and edit in place is probably a tossup..

opt=detectImportOptions('erik.dat','Delimiter',{'>','='},'ReadVariableNames',0);    % start with basic  object
opt.DataLines=[1 inf];                                              % it wants skip the second record on its own
opt.MissingRule='omitrow';                                          % this fixes up the bum row
opt.VariableTypes=[{'datetime','char'} repmat({'double'},1,6)];     % set the types since it can't tell with the Vxx=
opt=setvaropts(opt,3:8,'trimnonnumeric',1);                         % this strips the variable name
opt.SelectedVariableNames=opt.VariableNames([1 3:end]);             % the first V01 is second variable
opt=setvaropts(opt,"Var1","InputFormat",'yyyy/MM/dd HH:mm:ss');     % import datetime format
tErik=readtable('erik.dat',opt,'ReadVariableNames',0);

This returns

>> tErik
tErik =
  2×7 table
           Var1             Var2      Var3     Var4     Var5    Var6    Var7
    ___________________    ______    ______    _____    ____    ____    ____
    2021/07/20 17:32:11     81.00     80.00    10.20    0.00    0.00    0.00
    2021/07/20 17:33:04    100.00    100.00     5.00    0.00    0.00    0.00
>> 

This doesn't return the variable names; that can be managed by reading one record first and parsing it for the variable names that can be used to set them programmatically.