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tonygd's avatar
tonygd
Regular Visitor
9 years ago
Solved

Skip rows in CSV before it is parsed by Power BI

Hi, I have a number of reasonably large .csv files. Power BI is great at analysing them but only if I remove a number of rows of data (using Excel) from the top of each file before loading it in to Power BI. The reason I have to remove them is that these rows are effectively header info but they are in a number of different formats along each row and when Power BI attempts to parse the data it uses the first row to determine what it expects the rest of the data to be. This results in the actual data being parsed at the "wrong" comma and ending up useless, unless as I say I "pre-process" the data in Excel.

 

Is there any way (in Power BI) to strip out these header rows and only then parse the rows which compromise the rest of the data?

 

Thanks,

Tony

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  • tonygd's avatar
    tonygd
    9 years ago

    Hi Tom, Lydia,

     

    Unfortunately neither of your suggestions fixed the problem I was experiencing but I have found a solution.

     

    The .csv files I had been working with are generated as output from a portal and I had been trying to load them directly into PBI.

     

    It seems that if I open the .csv in Excel and save it (without making any changes) I can then load it into PBI with no problem...

     

    Not sure why this works, but it does...

     

    Thanks for your suggestions,

    Regards,

    Tony

9 Replies

  • TomMartens's avatar
    TomMartens
    Icon for Super User rankSuper User
    9 years ago

    Hey Tony,

     

    there is a way in Power Query

    1. Import the file
    2. Mark the complete table and choose "Remove Top Rows" from the context menu

     

    I guess this is what your are looking for

     

    Regards

    • tonygd's avatar
      tonygd
      Regular Visitor
      9 years ago

      Hi Tom,

       

      Thanks for the suggestion. Unfortunately that doesn't do the trick because the rest of the rows have already been parsed by Power BI based on what it detected in the first row..  :smileyfrustrated: .

       

      The challenge is that the "real data" is about 40 columns whereas the "header" is only about 6 columns so Power BI parses based on 6 columns meaning the the real data is wrapped and displaced...

       

      I really need some way of jumping over the 1st "n" rows before the data is parsed.

       

      Cheers,

      Tony                                                    

      • TomMartens's avatar
        TomMartens
        Icon for Super User rankSuper User
        9 years ago

        Hey,

         

        not sure what you mean by displaced. I created a sample file with

        20 rows of garbage at beginning (3 columns)

        10000 empty rows

        10 valuable rows with 40 columns

         

        The table contains 40 columns, of course the 10021st row has to be promoted as header and you also have to manually change the datatype of the column, but this has to be done just once and it's always a good idea to check the datatype.

         

        Maybe you have to check the option "Data Type Detection" (this was not necessary during my testing)

         

        Cheers

  • neilajr's avatar
    neilajr
    Regular Visitor
    4 years ago

    This is an old question but I never found a satisfactory answer elsewhere, so I'm sharing my solution to hopefully ease the pain for someone else.

     

    The way I found to skip n number of rows is to use the advanced editor.  This avoids having to mess about with any manual steps when oyu want to update the source csv:

    let    
    Source = Lines.FromBinary(File.Contents("C:/path_to_file.csv")),
    SkipN = List.Skip(Source,1), // Replace 1 with the number of rows you want to skip
    ConvertToTable = Table.FromList(SkipN, Splitter.SplitTextByDelimiter(","), null, null, ExtraValues.Error), //Assumes the delimiter is a comma
    #"Promoted Headers" = Table.PromoteHeaders(ConvertToTable, [PromoteAllScalars=true])
in
    #"Promoted Headers"

    Then select all your columns and run "detect data type" to simulate how PowerBI would detect data columns during the usual data connection process.

    • ABI_Rufino's avatar
      ABI_Rufino
      Icon for Advocate I rankAdvocate I
      1 year ago

      This is almost 100%, but you need to add QuoteStyle.Csv to the Lines.FromBinary, so quoted line breaks are treated as part of the data, not as the end of the current row:

      let    
    Source = Lines.FromBinary(File.Contents("C:/path_to_file.csv"), QuoteStyle.Csv),
    SkipN = List.Skip(Source,1), // Replace 1 with the number of rows you want to skip
    ConvertToTable = Table.FromList(SkipN, Splitter.SplitTextByDelimiter(","), null, null, ExtraValues.Error), //Assumes the delimiter is a comma
    #"Promoted Headers" = Table.PromoteHeaders(ConvertToTable, [PromoteAllScalars=true])
in
    #"Promoted Headers"