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  • pepperoni
    Member
    • Oct 2011
    • 59

    Newbler GSmapper output numMappedReads 2 results

    Hello, I am wondering why I get two very different results in the metrics of the Newbler GSmapper
    numMappedReads = 362295, 96.47%, 48.20%;
    numMappedBases = 51845395, 92.31%, 91.33%;
    which is the right percentage? the second one does not make any sense to me, does not coincide with the trimmed reads result or anything.
    thank you very much
  • sklages
    Senior Member
    • May 2008
    • 628

    #2
    Have a look at the sourrounding block. numMappedReads appears in different contexts.

    best, Sven

    Comment

    • pepperoni
      Member
      • Oct 2011
      • 59

      #3
      Originally posted by sklages View Post
      Have a look at the sourrounding block. numMappedReads appears in different contexts.

      best, Sven

      Sorry, I still don't get it, which sourrounding block? which contexts?

      thanks

      Comment

      • sklages
        Senior Member
        • May 2008
        • 628

        #4
        Roche manual states:

        Percentage metrics are calculated in two distinct ways, with the first percentage
        value of each pair calculated based on the number of reads (or bases) used in the
        mapping computation, and the second percentage value calculated from the total
        number of physical reads (i.e. number of sequences in the read files).
        hth, Sven

        Comment

        • pepperoni
          Member
          • Oct 2011
          • 59

          #5
          Thanks Sven, I just checked and my first reads in the metrics file coincide with what you told me

          first = percentage of total second = percentage of trimmed reads

          But then I have miseq paired data and in those the numbers didn't fit but now I've realized they are:

          first = percentage of trimmed reads second = half of it (one pair)

          I also noticed that for the number of bases is the other way round

          first = percentage of trimmed second = percentage of total
          Last edited by pepperoni; 05-08-2014, 07:44 AM.

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