问如何摆脱Python代码中嵌套的for循环？

EN

import numpy as np
import spacepy.time as spt
import datetime as dt

year=2001
for month in range (1,13):
        dmax=np.array([[31,28,31,30,31,30,31,31,30,31,30,31]]).T #number of days in a month
        for day in range(1,dmax[month-1]+1):
            for hour in range(24):
                for minute in range(60):

                D1=spt.Ticktock(dt.datetime(year, month, day, hour, minute, 0,0),'UTC').RDT #lower boundary of a minute

#here, spt is a spacepy.time, and '.RDT' returns GREGORIAN ORDINAL TIME.

                D2=spt.Ticktock(dt.datetime(year, month, day, hour, minute, 59,999999),'UTC').RDT #upper boundary of a minute

                mask=((time>D1)&(time<D2))

                electrons_logic=electrons[mask]
                k=(month-1)*dmax[month-1]*24*60+(day-1)*24*60+hour*60+(minute+1) #number of the minute in a year
                g[k,0]=np.nanmean(electrons_logic)