sporfire: calculate the avg per 15 minutes

问题

I am a beginner for Spotfire. I have a problem about the average calculation per each 15 mins by calculated column. A sample table could be like this:

id  time-stamp              value
 1  7/1/2016 12:01:01 AM    1.1
 2  7/1/2016 12:05:03 AM    0.9
 3  7/1/2016 12:08:04 AM    1.2
 4  7/1/2016 12:09:06 AM    0.8
 5  7/1/2016 12:12:09 AM    0.4
 6  7/1/2016 12:14:10 AM    0.6
 7  7/1/2016 12:15:12 AM    1.3
 8  7/1/2016 12:18:04 AM    1.4
 9  7/1/2016 12:21:06 AM    0.7
 10 7/1/2016 12:24:09 AM    1.7
 11 7/1/2016 12:31:10 AM    0.5
 12 7/1/2016 12:39:12 AM    1.3

I want to calculate the avg value for each 15 mins, the table is already ordered by time.
the final table I want to have is:

 time-stamp               Avg
 7/1/2016 12:00:00 AM    0.83333
 7/1/2016 12:15:00 AM    1.275
 7/1/2016 12:30:00 AM    0.9

for example, for the first number 0.83333 =(1.1+0.9+1.2+0.8+0.4+0.6)/6

it seems that I should identify an expression of the calculation for a new table, but how to calculate the avg. for each 15 mins. somebody could help me ?

thanks for your help :)

note: thanks for code @ksp585, but after this, i still have a small problem for it, the cross table just shows the times-stamp until 9:45 PM

回答1:

@ ZAWD - I have created a calculated column which groups the timestamp into 4 quarters for an hour. Used this column in the cross table below to calculate average time.

timestamp grouping expression (time_interval):

case  
when (DatePart("minute",[time-stamp])>0) and (DatePart("minute",[time-stamp])<15) then Date([time-stamp]) & " " & Hour([time-stamp]) & ":00" & ":00" 
when (DatePart("minute",[time-stamp])=15) and (DatePart("second",[time-stamp])>0) then Date([time-stamp]) & " " & Hour([time-stamp]) & ":15" & ":00" 
when (DatePart("minute",[time-stamp])>15) and (DatePart("minute",[time-stamp])<30) then Date([time-stamp]) & " " & Hour([time-stamp]) & ":15" & ":00" 
when (DatePart("minute",[time-stamp])=30) and (DatePart("second",[time-stamp])>0) then Date([time-stamp]) & " " & Hour([time-stamp]) & ":30" & ":00" 
when (DatePart("minute",[time-stamp])>30) and (DatePart("minute",[time-stamp])<45) then Date([time-stamp]) & " " & Hour([time-stamp]) & ":30" & ":00" 
when (DatePart("minute",[time-stamp])=45) and (DatePart("second",[time-stamp])>0) then Date([time-stamp]) & " " & Hour([time-stamp]) & ":45" & ":00" 
when (DatePart("minute",[time-stamp])>45) and (DatePart("minute",[time-stamp])<=60) then Date([time-stamp]) & " " & Hour([time-stamp]) & ":45" & ":00" 
when (DatePart("minute",[time-stamp])=0) and (DatePart("second",[time-stamp])>0) then Date([time-stamp]) & " " & Hour([time-stamp]) & ":00" & ":00"
else null end

Final Table:

Tested with a different datetime format:

来源：https://stackoverflow.com/questions/39333263/sporfire-calculate-the-avg-per-15-minutes

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average

spotfire