Read string and numeric array in CSV file

Hello,

I am trying to automatize the post-processing of csv files such as the one enclosed here.

I want to extract :

• the value of Hresolution
• the four columns of data

I have tried to use readtable but I can not figure out which options to select.

Thanks for your help

Answer 1

[Cris LaPierre]

If you save your file as a 'xlsx' file, you could take advantage of the 'Range' option in readtable.

Without it, you may have to be a little more creative. The approach I took was to disable a lot of the autodetection readtable uses. This approach means your files must all have the same format. Some of the 'header' values look incorrect because this approach treats them all as numeric values. Those that aren't get read in as NaN.

file = 'https://www.mathworks.com/matlabcentral/answers/uploaded_files/1076420/LDB100B.CSV';
data = readtable(file,'ReadRowNames',true,'ExpectedNumVariables',5,'PartialFieldRule','fill','numheaderlines',0)

data = 41970×4 table
                         Var2          Var3        Var4      Var5 
                       _________    __________    ______    ______

    Header Size               15           NaN       NaN       NaN
    Model Name               NaN           NaN       NaN       NaN
    Comment                  NaN           NaN       NaN       NaN
    BlockNumber                1           NaN       NaN       NaN
    TraceName                NaN           NaN       NaN       NaN
    BlockSize              41955         41955     41955     41955
    VUnit                    NaN           NaN       NaN       NaN
    SampleRate                 5             5         5         5
    HResolution              0.2           0.2       0.2       0.2
    HOffset               -18018        -18018    -18018    -18018
    HUnit                    NaN           NaN       NaN       NaN
    DisplayPointNo.            1             1         1         1
    PhaseShift                 1             1         1         1
    Date                     NaN           NaN       NaN       NaN
    Time                     NaN           NaN       NaN       NaN
    Row16              0.0001725    0.00017167       1.6    1.6417

hRes = data{'HResolution',1}

hRes = 0.2000

vals = data{(data{'Header Size',1}+1):end,:}

vals = 41955×4

0.0002 0.0002 1.6000 1.6417 0.0002 0.0002 1.6000 1.6417 0.0002 0.0002 1.6000 1.6417 0.0002 0.0002 1.6000 1.6417 0.0002 0.0002 1.6000 1.6417 0.0002 0.0002 1.6000 1.6417 0.0002 0.0002 1.6000 1.6417 0.0002 0.0002 1.6000 1.6417 0.0002 0.0002 1.6000 1.6417 0.0002 0.0002 1.5996 1.6417