Fast way to build special datetime range in python-CodePudding

I have two lists. One is list of datetime assume: d (10000 elements), one is list of int assume: m (1000 elements).

I would like to generate a new list of datetime, which is the shift of m minutes of d.

To put it more intuitively, I am trying to do following code:

[x   datetime.timedelta(minutes = y) for x in d for y in m]

The trouble is the speed is very slow for above double loops. Is there any faster way to handle it? Thanks.

CodePudding user response：

To reduce time, just reuse datetime.timedelta(minutes=y). For example, trade a little space with the run time.

M = [ datetime.timedelta(minutes=y) for y in range(1000)]  # trade space
[x   y for x in d for y in M] # save time

Example:

import datetime,time

d = [ datetime.date(2022, 10, _0 1 ) for _ in range(10000)]
m = [ _ for _ in range(1000) ] 
M = [ datetime.timedelta(minutes = y ) for y in range(1000)] 

start_time = time.time()
[x   datetime.timedelta(minutes = y) for x in d for y in m]
print("from time: {}".format(time.time() - start_time))

start_time = time.time()
result = [x   y for x in d for y in M]
print("to time: {}".format(time.time()-start_time))

The Output:

from time: 7.302632093429565
to time: 0.6205151081085205