Python study notes - the use of time library

time acquisition

time()

Used to obtain the current timestamp, that is, the internal time value of the computer, which is a floating point number (the number of seconds from January 1, 1970 to the present)

import time
print(time.time())

result

1642520186.166802

ctime()

Used to get the current time and represent it in a human-readable way, returning a string

import time
print(time.ctime())

result

Tue Jan 18 23:36:26 2022

gmtime()

Used to get the current time, expressed as a computer-processable time format

import time
print(time.gmtime())

result

time.struct_time(tm_year=2022, tm_mon=1, tm_mday=18, tm_hour=15, tm_min=36, tm_sec=26, tm_wday=1, tm_yday=18, tm_isdst=0)

time formatting

formatter

format string	Date/Time Description
%Y	years
%m	month
%B	month name
%b	abbreviated month name
%d	date
%A	Week
%a	week abbreviation
%H	Hour (24h system)
%l	Hour (12h system)
%p	am/pm
%M	minute
%S	Second

strftime(tpl,ts)

tpl is a format template string used to define the output effect
ts is the type of time variable inside the computer

import time
t=time.gmtime()
#   %A     星期
#   %p     上下午
#strftime()将时间按照特定格式输出
print(time.strftime("%Y-%m-%d %A %H:%M:%S %p",t))

result

2022-01-18 Tuesday 15:44:26 PM

strptime(str,tpl)

str is the time value in the form of a string
tpl is a formatted template string used to define the output effect

import time
t=time.gmtime()
#striptime()将一个时间字符串转化为计算机时间struct_time()形式
timeStr='2022-01-17 23:24:30'
print(time.strptime(timeStr,"%Y-%m-%d %H:%M:%S"))

result

time.struct_time(tm_year=2022, tm_mon=1, tm_mday=17, tm_hour=23, tm_min=24, tm_sec=30, tm_wday=0, tm_yday=17, tm_isdst=-1)

program timing

Program timing refers to the process of measuring the elapsed time of starting and stopping actions

perf_counter()

Returns a CPU-level precise time count value in seconds.
Since the starting point of this count value is uncertain, it makes sense to call the difference continuously

import time
start_time = time.perf_counter()
print(start_time)
end_time = time.perf_counter()
print(end_time)
print(end_time-start_time)

result

0.7581596
0.7581973
3.7699999999918354e-05

sleep(s)

s The sleep time, in seconds, can be a floating point number

import time
time.sleep(3)
print("程序休眠了3秒")

The program will output after 3 seconds

程序休眠了3秒

Example: Text Progress Bar

The first experience of the text progress bar

import time
scale=20
print("{:-^20}".format("执行开始"))
for i in range(scale+1):
    a='='*i
    b='-'*(scale-i)
    c=i/scale*100
    print("{:3.0f}%[{}>{}]".format(c,a,b))
    time.sleep(0.2)
print("{:-^20}".format("执行结束"))

result

--------执行开始--------
  0%[>--------------------]
  5%[=>-------------------]
 10%[==>------------------]
 15%[===>-----------------]
 20%[====>----------------]
 25%[=====>---------------]
 30%[======>--------------]
 35%[=======>-------------]
 40%[========>------------]
 45%[=========>-----------]
 50%[==========>----------]
 55%[===========>---------]
 60%[============>--------]
 65%[=============>-------]
 70%[==============>------]
 75%[===============>-----]
 80%[================>----]
 85%[=================>---]
 90%[==================>--]
 95%[===================>-]
100%[====================>]
--------执行结束--------

Text progress bar single line dynamic refresh

import time
print("{:-^20}".format("执行开始"))
scale=20
for i in range(scale+1):
    a='='*i
    b='-'*(scale-i)
    c=i/scale*100
    #\r使光标回到行首，end=""使输出不换行
    print("\r{:3.0f}%[{}>{}]".format(c,a,b),end="")
    time.sleep(0.2)
print("\n"+"{:-^20}".format("执行结束"))

result

The full effect of the text progress bar

import time
scale=50
print("执行开始".center(scale//2,"-"))
start=time.perf_counter()
for i in range(scale+1):
    a='='*i
    b='-'*(scale-i)
    c=i/scale*100
    dur=time.perf_counter()-start
    print("\r{:3.0f}%[{}>{}]{:.2f}s".format(c,a,b,dur),end="")
    time.sleep(0.2)
print("\n"+"执行结束".center(scale//2,"-"))

result

The above is the content organized by the courseware of MOOC teacher Songtian, which is used for personal review