Readtable() Skipps last rows of csv

Hello there,

I have some issues with importing and exporting data.

I am summerizing some measurment data in one script which then saves the summarized data in a csv file for easy sharing (using writetable(table, filename).

Now I would like to import this data to work with it again and therefore I try to import it using readtable(filename).

The issue ist, that I export a 392x10 table and it only imports a 323x10 table. It just skipps the last 70 rows somehow.

When I open the csv-file in excel I can see that the export worked fine.

%Script 1
...
filename = 'measurementdata.csv';
writetable(table,filename);

Import said file in different script

%Script 2
table2 = readtable('measurementdata.csv');

%Access colums by name
temps = unique(table2.targTemp);
volts = unique(table2.targVlt);
curr = unique(table2.targCurr);
...

I have attached the measurmentdata.csv file

Answer 1

[Star Strider]

If you are using the unique function before writing the output file, it could be deleting several entries. Also, the correct approach is likely to be:

table2u = unique(table2, 'rows');

to avoid scrambling the individual columns (variables).

I have not checked by looking at it in Excel, however it appears to be read correctly (as a (392x8) table) in R2022a —

T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1052370/measurementdata.csv', 'VariableNamingRule','preserve')

T1 = 392×8 table
    targVlt    targCurr    targTemp    maxTrq      minTrq     avgTrq     maxCurr    minCurr
    _______    ________    ________    _______    ________    _______    _______    _______

       9         2500         23       0.78394    -0.44696    0.65847    15.637     -1.5509
       9         2500         23       0.76172     -1.3036    0.64853    18.255     -1.7725
       9         3500         23        1.0045    -0.51398    0.88617    35.812     -3.2562
       9         3500         23       0.97003     -1.2741    0.86851    44.714      -18.51
       9         4500         23        1.2412    -0.50653     1.0606    50.388     -12.857
       9         4500         23        1.1934      -1.181     1.0497    43.586     -9.7418
       9         5500         23        1.2456    -0.52069     1.1492    56.457     -17.087
       9         5500         23        1.2357     -1.2138     1.0815    43.842     -16.798
      11         2500         23       0.74036     -0.5166    0.66467    11.111     -1.3696
      11         2500         23       0.80347     -1.1976    0.65165    15.402     -4.4647
      11         3500         23       0.95367    -0.52124    0.86345    22.256     -7.0294
      11         3500         23       0.99969     -1.3061    0.85621    27.836     -6.6467
      11         4500         23        1.1523    -0.52136     1.0639    38.376     -17.577
      11         4500         23        1.1912      -1.285     1.0513    42.982     -19.054
      11         5500         23        1.3141    -0.53064     1.1485      52.1     -1.6852
      11         5500         23        1.2513      -1.252     1.1352    46.373     -4.6527

LastRow = T1(392,:)

LastRow = 1×8 table
    targVlt    targCurr    targTemp    maxTrq     minTrq     avgTrq     maxCurr    minCurr
    _______    ________    ________    _______    _______    _______    _______    _______

     15.5        2500        120       0.62531    -1.7099    0.53204    21.035     -2.605 

Check to be sure all the updates to R2017b are downloaded and installed, since there could be a bug that was subsequently fixed. (I no longer have R2017b installed here, so I cannot test it.)

.

[Cris LaPierre]

I have R2017a installed on my computer. When I use the code you provided to import your csv file, I get a 392x8 table.

When I open your csv file in Notepad++, there are only 8 columns of data, so not sure why you are expecting 10. Perhaps you have not shared the correct file?

[Star Strider]

@Cris LaPierre — Thank you!

[Tim Rothhaupt]

Thanks for the answer.

That was my bad. The newest table is only 8 columns, but still it is the correct file.

I've checked for Matlab Updates and now it seems to be working. Must have been a bug somehow.

[Star Strider]

As always, my pleasure!