在 Python 中检查模数的更快方法

Question

I've been writing simulation codes for a while, and there's always a main loop that looks like this, in this case in Python:

while t<totalTimesteps:
    
    t += 1
    processOneTimestep()

    outputData()

the line outputData() writes results to a file one per timestep for analysis. This writing can take quite a bit of time, and we usually don't need the state of whatever we are doing in every single timestep, so it will usually look like this:

while t<totalTimesteps:
    
    t += 1
    processOneTimestep()

    if t%N == 0:
        outputData()

where N is an integer that sets how often we write. Assuming the simulation and writing themselves are very optimized, is there a way in Python to accelerate that modulus check, or to use inline Python magic to make it faster? Is that if line as fast as it can be in Python?

Answer 1

I don't know if it's faster, but you could use nested loops.

for tsteps in range(0, totalTimesteps, N):
    for t in range(tsteps, min(tsteps+N, totalTimesteps)):
        processOneTimestep()
    outputData()

Answer 2

You could use map to apply a function to all index. To get all the different index you could use range, and you could use a lambda function to get a more concise code.

N=3 #example N

map(
    lambda i: (processOneTimestep(), outputData()) if i%N==0 else processOneTimestep(),
    range(totalTimesteps)
)

This code would execute both functions when i%N==0 in other case will only execute processOneTimestep()