问题
I'm making a summary of a list of tasks, and the corresponding dates (start date, first answer date, ...).
It looks more or less like the following:
Title Start date First answer
Task1 29/06/2018 02/07/2018
Task2 09/05/2018
Task3 13/06/2018 14/06/2018
I would like to calculate the average time, needed for the first answer to be given. In case no first answer is given yet, this entry needs to be ignored in the calculation of the average.
In order to be able to understand the formulas better, I've decided to use names for the headers, like:
Name "Header_Title" has value "Title"
Name "Header_Start_Date" has value "Start Date"
Name "Header_First_Answer" has value "First answer"
Also, the number of entries, defined as COUNTA(OFFSET(Header_Title;1;0):A1048576) has a name: Total_Count.
Next to that, I've created names for the ranges of the column values:
"All_Start_Dates" is defined as =OFFSET(Header_Start_Date;1;0):OFFSET(Header_Start_Date;Total_Count;0)
"All_First_Answered" is defined as =OFFSET(Header_First_Answer;1;0):OFFSET(Header_First_Answer;Total_Count;0)
Explanation : take the first entry under the header (column title) and go to the row, corresponding to the last task.
This makes it very easy to write a formula for calculating the average difference between those date columns:
{=AVERAGE(All_First_Answered_Dates-All_Start_Dates)}
// mind the {} for showing this is an array formula
Now the problem is: how to use the AverageIf worksheet function in order not to take into account the cases where First answer is not filled in?
I already tried using ">0" and ">"&0, but this does not work, the formulas are said not to be valid:
{=AVERAGEIF(All_First_Answered_Dates-All_Start_Dates;">0")}
{=AVERAGEIF(All_First_Answered_Dates-All_Start_Dates;">"&0)}
Does anybody have an idea?
Thanks in advance
P.s.1. As you can see, I'm using cell range A1048576 as the last entry of column A, does anybody know a more elegant way to describe this?
P.s.2. One extra thing, which would make my life easier, is the possibility to see which cells have a name (I was thinking about conditional formatting, but I didn't find the way to do this). Does anybody know if there is a way to highlight individual cells, linked to a name?
回答1:
So my suggested answer would be
=AVERAGEIF(All_First_Answered,">0")-AVERAGEIF(All_First_Answered,">0",All_Start_Dates)
I'm assuming here that all start dates are present but first answered dates may be missing: you could easily add an extra condition for start date if you used AVERAGEIFS. Both parts of the formula include the same conditions so they are working on the same rows.
The intermediate columns above are just included by way of explanation.
回答2:
Try an array formula.
If you're not familiar with array formulas, the significant difference is you press and hold Ctrl+Shift then hit Enter instead of just pressing Enter. You will see the formula preceded and followed by curly brackets. Do not type those. Those will appear automatically.
=AVERAGE(IF(INDIRECT("C14:C"&LOOKUP(2,1/(A:A<>""),ROW(A:A)))=0,"",INDIRECT("C14:C"&LOOKUP(2,1/(A:A<>""),ROW(A:A)))-INDIRECT("B14:B"&LOOKUP(2,1/(A:A<>""),ROW(A:A)))))
来源：https://stackoverflow.com/questions/51403707/how-to-use-averageif-worksheet-function-for-calculating-average-date-differences