3 Replies Latest reply on Nov 13, 2018 11:42 AM by Zach Leber

    Tableau incorrectly reads values as nulls

    David Hou

      I have a very simple text file (attached).  All the columns are correctly read into Tableau with the exception of the RF_Frequency column.  Looking at the raw data, you can see that a few of the rows have a nonzero value.  However, Tableau treats all these values as nulls for some reason (it correctly reads everything else as zero).  The file opens correctly in Excel where I can plot against the time column, but I can't seem to do this Tableau.  Can someone help?

        • 1. Re: Tableau incorrectly reads values as nulls
          Jim Dehner


          please attach your twbx workbook with your attempt to open the file - I did not have a problem




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          • 2. Re: Tableau incorrectly reads values as nulls
            David Hou

            Thanks for the reply.  Even in your table, it reads the sum of all frequencies as zero.  However, if you open the raw text file (not in Tableau) you will find values of frequency where it is non-zero.  For example, in the attached excel workbook, you can clearly see there are non-zero values of frequency.  If you generate the same plot in Tableau, it will just be a flat line (my twbx is attached).

            • 3. Re: Tableau incorrectly reads values as nulls
              Zach Leber

              Tableau's text file readers use row sampling to determine the data type. The original JET connector looked at something like the first 25 rows, the new connector may look at 1000, but if your data is sparse it will assume the entire column is filled with integer zeros, and fail to read any of your floating point numbers. You can confirm this by re-exporting your .txt file sorted with the non-zero RF frequencies at the top of the list. Read that into Tableau and you will see values.

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