How to read a text file with irregular timestamp data using detectImportOptions function ?

I want to read the condition monitoring datas stored in the text file. The data text file has 7 colums, where the first colum represents the sample time and the rest are the sensor datas. Portion of the data is illustrated in the attached file. I have tried to use the detectImportOptions function for importing the data into MATLAB workspace, yet the detectImportOptions function can not detect the file content correctly. Which function should I use to import this data file ?

opts = detectImportOptions("sampleDataFile.txt","Delimiter"," ");
preview("sampleDataFile.txt",opts)

Warning: Column headers from the file were modified to make them valid MATLAB identifiers before creating variable names for the table. The original column headers are saved in the VariableDescriptions property.
Set 'VariableNamingRule' to 'preserve' to use the original column headers as table variable names.

ans = 8×1 table
         x2010_09_12_20_48_21_00000__07000_356317_0_416615_0_0462520_066468_0_0623550_018159     
    _____________________________________________________________________________________________

    {'2010-09-12_20:48:21.00005_-0700→0.340215→-0.142868→0.050365→-0.062355→0.002056→-0.142868' }
    {'2010-09-12_20:48:21.00010_-0700→0.324112→-0.319999→-0.014046→-0.078457→0.002056→0.002056' }
    {'2010-09-12_20:48:21.00015_-0700→0.034262→0.163084→-0.094560→-0.062355→-0.046252→0.018159' }
    {'2010-09-12_20:48:21.00020_-0700→0.179187→-0.158971→0.034262→0.002056→-0.062355→0.018159'  }
    {'2010-09-12_20:48:21.00025_-0700→0.130879→-0.046252→0.018159→-0.062355→-0.014046→0.002056' }
    {'2010-09-12_20:48:21.00030_-0700→0.324112→-0.223382→0.082570→-0.062355→0.050365→-0.046252' }
    {'2010-09-12_20:48:21.00035_-0700→-0.094560→0.098673→-0.014046→-0.110663→-0.046252→0.018159'}
    {'2010-09-12_20:48:21.00040_-0700→0.211392→-0.175074→-0.046252→0.050365→0.002056→0.018159'  }

Answer 1

[Stephen23]

The file that you uploaded is tab delimited, not space delimited as you specified. Once you provide the correct delimiter importing the file content will be a lot easier:

fnm = 'sampleDataFile.txt';
opt = detectImportOptions(fnm, 'Delimiter','\t');
preview(fnm,opt)

ans = 8×7 table
                   Var1                      Var2        Var3         Var4         Var5         Var6         Var7   
    ___________________________________    ________    _________    _________    _________    _________    _________

    {'2010-09-12_20:48:21.00000_-0700'}     0.35632     -0.41662    -0.046252     0.066468    -0.062355     0.018159
    {'2010-09-12_20:48:21.00005_-0700'}     0.34021     -0.14287     0.050365    -0.062355     0.002056     -0.14287
    {'2010-09-12_20:48:21.00010_-0700'}     0.32411        -0.32    -0.014046    -0.078457     0.002056     0.002056
    {'2010-09-12_20:48:21.00015_-0700'}    0.034262      0.16308     -0.09456    -0.062355    -0.046252     0.018159
    {'2010-09-12_20:48:21.00020_-0700'}     0.17919     -0.15897     0.034262     0.002056    -0.062355     0.018159
    {'2010-09-12_20:48:21.00025_-0700'}     0.13088    -0.046252     0.018159    -0.062355    -0.014046     0.002056
    {'2010-09-12_20:48:21.00030_-0700'}     0.32411     -0.22338      0.08257    -0.062355     0.050365    -0.046252
    {'2010-09-12_20:48:21.00035_-0700'}    -0.09456     0.098673    -0.014046     -0.11066    -0.046252     0.018159

Note that calling DETECTIMPORTOPTIONS is not required, you can simply call READTABLE directly:

tbl = readtable(fnm, 'Delimiter','\t');
tbl.Var1 = datetime(tbl.Var1, 'TimeZone','-07:00', 'InputFormat','u-M-d_H:m:s.SSSSS_Z', 'Format','u-MM-dd HH:mm:ss.SSSSS Z')

tbl = 20×7 table
                 Var1                    Var2         Var3         Var4         Var5         Var6         Var7   
    _______________________________    _________    _________    _________    _________    _________    _________

    2010-09-12 20:48:21.00000 -0700      0.35632     -0.41662    -0.046252     0.066468    -0.062355     0.018159
    2010-09-12 20:48:21.00005 -0700      0.34021     -0.14287     0.050365    -0.062355     0.002056     -0.14287
    2010-09-12 20:48:21.00010 -0700      0.32411        -0.32    -0.014046    -0.078457     0.002056     0.002056
    2010-09-12 20:48:21.00014 -0700     0.034262      0.16308     -0.09456    -0.062355    -0.046252     0.018159
    2010-09-12 20:48:21.00020 -0700      0.17919     -0.15897     0.034262     0.002056    -0.062355     0.018159
    2010-09-12 20:48:21.00025 -0700      0.13088    -0.046252     0.018159    -0.062355    -0.014046     0.002056
    2010-09-12 20:48:21.00029 -0700      0.32411     -0.22338      0.08257    -0.062355     0.050365    -0.046252
    2010-09-12 20:48:21.00035 -0700     -0.09456     0.098673    -0.014046     -0.11066    -0.046252     0.018159
    2010-09-12 20:48:21.00040 -0700      0.21139     -0.17507    -0.046252     0.050365     0.002056     0.018159
    2010-09-12 20:48:21.00045 -0700    -0.014046      0.14698     -0.15897    -0.078457    -0.030149     0.018159
    2010-09-12 20:48:21.00050 -0700      0.37242     -0.28779     -0.09456      0.11478     0.018159     -0.09456
    2010-09-12 20:48:21.00055 -0700    -0.014046      0.14698    -0.030149    -0.062355     0.050365    -0.062355
    2010-09-12 20:48:21.00059 -0700      0.08257     -0.09456     -0.25559     0.066468     0.002056     0.002056
    2010-09-12 20:48:21.00065 -0700    -0.078457     0.050365    -0.078457     0.098673    -0.062355     0.002056
    2010-09-12 20:48:21.00070 -0700      0.11478     -0.23949     -0.15897      0.08257    -0.046252    -0.046252
    2010-09-12 20:48:21.00075 -0700      0.14698     0.034262     0.098673     0.034262    -0.078457    -0.078457

Note that REDATBLE does not handle timezones, so you will have to call DATETIME afterwards.

[Chuguang Pan]

@Stephen23. Thanks a lot for your help.