Categorizing time data into 15 minute periods.

[bwaites]

Hi!

I have a large group of data which has number of bat calls (split by species) and then the time of each the calls.
I would like to group the calls into 15 minute periods in relation to sunset eg 15 minutes before sunset, 0-15 minutes after sunset, 15-30 minutes after sunset, 30-45 mins after and so on.

Is there an formula i can use to group the data in this way?

The next bit which i have struggled with is that when it goes past midnight, i would still like it to continue, however currently whatever i try excel is seeing it as a the next day and getting the time completely wrong.
For example if a have a bat call at 4am and sunset was at 7pm the night before excel is registering it as being 15hrs early rather than 9 hours later.


Here is a example version of what i have currently (but a lot less!)

[TABLE="width: 500"]
<tbody>[TR]
[TD]Time[/TD]
[TD]Common Pipistrelle[/TD]
[TD]Soprano Pipistrelle[/TD]
[TD]Brown long-eared[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]19:01[/TD]
[TD]36[/TD]
[TD]1[/TD]
[TD]1[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]19:02[/TD]
[TD]57[/TD]
[TD]7[/TD]
[TD]0[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]19:03[/TD]
[TD]32[/TD]
[TD]6[/TD]
[TD]0[/TD]
[TD][/TD]
[/TR]
[TR]
[TD]19:07[/TD]
[TD]31[/TD]
[TD]12[/TD]
[TD]4[/TD]
[TD][/TD]
[/TR]
</tbody>[/TABLE]

 

[steve the fish]

If you want to use time that spans more than one day then the simplest way is it needs a date component too. Time to excel is a fraction of 1. A day is 1. Date times such as 22/10/2018 09:14 is just a number (43395.3847222222) formatted to look like a date time. The 43395 is the number of days since 01/01/1900. The 0.384722 is the fraction of a day that has passed ie 9 hours 14 mins past midnight. Hope that explains that. To group your data you first need to sort out your date times so things that happen after midnight get placed correctly.

 

[Norie]

To the times in the time column have a date part?