Excel difficult should be easy, calculate average between two non-missing entries with date-time in a column

Question

I have to calculate average consumption for corresponding time frames (while table also contains other data). I have a table with date and time columns (european format) and a column with occasional counter state (fetched from text column with =IF(ISNUMBER(SEARCH("count.state.";E1));MID(E1;FIND("count.state.";E1)+12;5);""). I would like to calculate average consumption automatically instead of having to manually select ranges, edit formula, then copy etc.

    A       B       F       G
1   2.12.   23:00   10765   =INDEX/MATCH formula should use the same data as 3 rows below 
2   3.12.   8:00    ""      =INDEX/MATCH formula should use the same data as 2 rows below 
3   3.12.   11:00   ""      =INDEX/MATCH formula should use the same data as in the row below 
4   3.12.   18:00   10769   =(10769 - 10765) / (3.12.18:00 - 2.12.23:00)
5   3.12.   23:00   ""      =INDEX/MATCH formula should use the same data as 5 rows below 
6   4.12.   11:00   ""      =INDEX/MATCH formula should use the same data as 4 rows below 
7   4.12.   15:00   ""      =INDEX/MATCH formula should use the same data as 3 rows below 
8   4.12.   18:00   ""      =INDEX/MATCH formula should use the same data as 2 rows below 
9   4.12.   23:00   ""      =INDEX/MATCH formula should use the same data as in the row below 
10  5.12.   18:00   10786   =(10786 - 10769) / (5.12.18:00 - 3.12.23:00)

I am learning to use Excel functions but this seems to be way way over my head. Anyone has a solution to this challenge? Thanks for your patience and effort.

Miki

Answer 1

Well OK maybe not the elegant solution you're looking for but it gets the job done.

The idea is just to use helper columns to copy the date/time and counter reading from the row containing the last counter reading down through all the rows up to the one before the next counter reading like this

=IF(ISNUMBER(F2),F2,H1) for the counter starting in H2

=IF(ISNUMBER(F2),G2,I1) for the date/time starting in I2

then when you get to the row containing the next counter reading, do the calculation.

My column G contains the date & time put together using

=DATEVALUE(A2&"2014")+B2 starting in G2.

I have taken the liberty of changing the dots in the dates to slashes because of my locale.

Then the actual calculation is

=IF(AND(ISNUMBER(F2),ISNUMBER(I1)),(H2-H1)/(I2-I1),"")

To copy the result back through each time period I have started at the bottom in cell K11 and pulled the formula upwards

=IF(ISNUMBER(J11),J11,K12)

It looks like this

However there is a useful discussion of finding the first and last cell with a numerical entry here which leads to the formula

=IFERROR((INDEX(F2:F$11,MATCH(1,INDEX(ISNUMBER(F2:F$11)+0,0),0))-(INDEX(F$1:F1,MATCH(9E+307,F$1:F1,1))))/(INDEX(G2:G$11,MATCH(1,INDEX(ISNUMBER($F2:F$11)+0,0),0))-(INDEX(G$1:G1,MATCH(9E+307,F$1:F1,1)))),"")

to be placed in H2 and pulled down and is a direct way of finding the answers.

I know which I prefer.