Calculate RTT with 3 decimal places in Python 3

Question

I have a simple UDP client–server program and I get the time in ms of sending a packet and the time in ms of receiving the packet like this:

send_time_ms = int(round(time.time() * 1000))
# sending the packet
# ...
# receiving the packet
recv_time_ms = int(round(time.time() * 1000))

For example, I get 1430645866889 and 1430645866898. I would like to then find the difference between these two values and round it to a value with 3 decimal places, like 0.291 and so on. I tried subtracting them, but it gave me 9 or 10.0 in float. I must be doing this wrong.

Could you please help me find a way to edit the time.time() code so I can do this?

Answer 1

Use the second argument of round which indicates the number of numbers after the decimal:

send_time_ms = time.time()
...
recv_time_ms = time.time()
rtt_in_ms = round(recv_time_ms - send_time_ms, 3)