How to round time to days?

[Tommie Thompson]

I have a variable of datetime. For instance:

1/3/15 12:23:33
3/5/15 15:31:01
5/2?15 01:01:2

I want to round it in two ways. First, how do I round it to 00:00:00? For instance, I want the first row to become "1/3/15 00:00:00." Second, how do I round it up to the last second of the day? For instance, I want the first row to become "1/3/15 23:59:59." Sorry for not using -dataex-. I tried it, but it wouldn't spit out the values in %tc format.

[Clyde Schechter]

* Example generated by -dataex-. To install: ssc install dataex
clear
input double time
1735907013000
1741188661000
1746147680000
end
format %tc time

gen double round_down = cofd(dofc(time))
gen double round_up = cofd(dofc(time) + 1) - 1000
format round_* %tc

list, noobs clean

Notes:

1. As you can see from the above, -dataex- specifically does not put out something that human eyes will recognize as dates and times. It's not supposed to. It puts out the double-precision numbers that Stata uses internally, and then a command to apply %tc formatting to them.

2. The third observation in your example is not a valid date-time. I assume you made some typos in creating the example, and I made a possible correction.

[Tommie Thompson]

Thanks!