6 Replies Latest reply: Sep 30, 2011 5:46 AM by Jesper Almar RSS

    Average of all first/last records

      I want to calculate the average  of the first and the last record in each group described in the example below.

       

      An average  of first/last "A" and first Last "B"

       

      Example

       

      NameSequenceValue
      A1110
      A2220
      A3315
      A4410
      A5520
      NameSequenceValue
      B1115
      B2210
      B3310
      NameSequenceValue
      A615
      A7220
      A8330
      A9415
      NameSequenceValue
      B4130
      B525
      B6310
      B7420

       

       

      First A : AVG(10+5)

      First B: AVG(15+30)

      Last A: AVG(5+15)

      Last B: AVG(20+20)

       

      I can't figure out how to find the last record in a group and afterwards  find the average of all the last records.

       

      Hope somebody can help me with an answer.

        • Average of all first/last records
          Sunil Chauhan

          for last recrd use

           

          set last_var=peek('fieldname',-1,'tablename')

           

          fisrt recard

          set First_var=peek('fieldname',0,'tablename')

           

           

          and then in expression

           

          (last_var +First_var)/2

            • Average of all first/last records

              Thank You for the answer.

               

              My problem is not to find the average between the first and the last record but the average of all the first records or all the last records named A or B

               

              Ex

              Find the last record in group A1-A5

              Find the last record in group A6-A9

              Find the last record in group Ax-Ay

              Find the average of all the results.

                • Average of all first/last records
                  Stefan Wühl

                  Hi Jesper,

                   

                  is there a way that you can determine the Group / Subgroup of records?

                   

                  I.e.

                  A1-A5 could be Group A, subgroup 1

                  A6-A9 Group A, subgroup 2

                  B1-B3 Group B, subgroup 1

                  B4-B7 Group B, subgroup 2

                  etc..

                   

                  I think you could use something like Left(Name,1) for Group and somehow the restart of indexing for subgroup increment, but do you have this information maybe already in your model?

                   

                  Regards,

                  Stefan

                    • Average of all first/last records

                      Hi Stefan

                       

                      My Groups/Subgroups are well defined.

                       

                      I have thousands of groups named A,

                      thousands of groups named B,

                      thousands of groups named C etc.

                       

                      Each group have about 50 records.

                       

                      I want to take the last record (defined bu sequence number) of each A group and then find the average of these records.

                       

                      Regards

                      Jesper

                        • Re: Average of all first/last records
                          Stefan Wühl

                          Hi,

                           

                          what I wanted to say was, how could we tell QV which Names belong to a subgroup? Sequence numbers are not unique.

                          I assume your names are ascending with Sequence numbers, so if e.g. A6 has a lower sequence number than A5, this will indicate that it belongs to a different subgroup, starting a new sequence numbering.

                           

                          I think if we had something like a subgroup index, that would make life much easier, since we can look for min and max sequence then per subgroup index.

                           

                          I assume you don't have this in your model, so let's create an index:

                           

                          Groups:

                          LOAD * INLINE [

                          Name,    Sequence,    Value

                          A1,    1,    10

                          A2,    2,    20

                          A3,    3,    15

                          A4,    4,    10

                          A5,    5,    20

                          B1,    1,    15

                          B2,    2,    10

                          B3,    3,    10

                          A6,    1,    5

                          A7,    2,    20

                          A8,    3,    30

                          A9,    4,    15

                          B4,    1,    30

                          B5,    2,    5

                          B6,    3,    10

                          B7,    4,    20

                          ];

                           

                          LOAD *,

                          Left(Name,1) as Group,

                          if (peek(Sequence)=Sequence-1 and previous(Left(Name,1))=Left(Name,1), peek(Subgroup), rangesum(peek(Subgroup))+1) as Subgroup

                          resident Groups order by Name asc;

                           

                          I assumed that your Groups are given by the first letter, probably that is simplying your real situation, so just use anything else to retrieve your Groups here (Group means the class for which you want to average the results later on). For example, use Keepchar(Name) instead of left().

                           

                          Now we are having Groups and subgroups, we can calculate the average of first and last sequences per subgroup and within groups like

                          =avg(aggr(FirstsortedValue(Value,Sequence),Group,Subgroup))

                           

                          for averaging the first sequence number values and

                           

                          =avg(aggr(FirstsortedValue(Value,-Sequence),Group,Subgroup))

                           

                          for averaging the last sequence number values.

                          (See also attached app. I put above two expression in a straight table with dimension Group).

                           

                          Regards,

                          Stefan