Master Python Time Handling: Timestamps, Calendar, datetime & Practical Tricks

In daily life and work we constantly interact with time, facing questions such as when to wake up, subway intervals, lunch breaks, weekdays, and adding scheduled tasks to code. This article explains Python's time‑related classes, methods, and attributes in detail.

1. Timestamp

1.1 Timestamp Overview

A timestamp is the number of seconds elapsed since 1970‑01‑01 UTC (Unix timestamp). It is used to ensure data ordering and consistency across systems.

Unix timestamps count seconds without leap seconds; one hour equals 3600 seconds, one day equals 86400 seconds.

1.2 Timestamp Conversion Websites

Useful online tools for converting between timestamps and human‑readable dates include:

站长工具: https://tool.chinaz.com/tools/unixtime.aspx

在线工具: https://tool.lu/timestamp/

Json在线解析: https://www.sojson.com/unixtime.html

菜鸟工具: https://c.runoob.com/front-end/852

北京时间工具: http://www.beijing-time.org/shijianchuo/

After covering timestamps, we focus on three Python libraries for date and time handling: calendar, time, and datetime.

2. calendar

The calendar module provides calendar‑style date displays.

2.1 Module Content

Example: display the calendar for 2020.

import calendar
year = calendar.calendar(2020)
print(year)

Changing parameters adjusts width and layout:

year = calendar.calendar(2020, w=3, l=1, c=8)
print(year)

Parameters meaning:

c: month spacing

w: day column width

l: number of rows per week

Other useful functions: calendar.isleap(year): returns True if the year is a leap year. calendar.leapdays(y1, y2): counts leap years in the interval [y1, y2). calendar.month(year, month, w=2, l=1): returns a string calendar for a specific month. calendar.monthcalendar(year, month): returns a list of weeks, each week a list of day numbers (0 for days outside the month). calendar.monthrange(year, month): returns a tuple (weekday of first day, number of days in month). calendar.weekday(y, m, d): returns the weekday (0‑6, Monday‑Sunday).

3. time

The time module is the most commonly used module for time operations.

3.1 Core Functions

time.time()

: current timestamp. time.localtime([secs]): convert a timestamp to a time tuple (local time). time.gmtime([secs]): convert a timestamp to a UTC time tuple. time.asctime([t]): format a time tuple as a readable string. time.ctime([secs]): convert a timestamp to a readable string. time.mktime(t): convert a local time tuple to a timestamp. time.strftime(fmt, t): format a time tuple according to fmt. time.strptime(string, fmt): parse a string into a time tuple.

3.2 Example Usage

import time
now_timestamp = time.time()
now_tuple = time.localtime(now_timestamp)
print(time.strftime("%Y/%m/%d %H:%M:%S", now_tuple))

Converting a specific timestamp:

timestamp = 1608852741
t = time.localtime(timestamp)
print(time.strftime("%Y/%m/%d %H:%M:%S", t))

4. datetime

When time is insufficient, the datetime module offers richer functionality.

4.1 Key Classes

date

: year, month, day. time: hour, minute, second, microsecond. datetime: combination of date and time. timedelta: duration between two dates/times. tzinfo: time‑zone information.

4.2 Example: Working with date

from datetime import date
today = date.today()
print("Current date:", today)
print("Year:", today.year)
print("Month:", today.month)
print("Day:", today.day)
print("Weekday (0=Mon):", today.weekday())

4.3 Example: Working with datetime

from datetime import datetime, time, timezone, timedelta
# Current datetime
print(datetime.now())
# From timestamp
print(datetime.fromtimestamp(1697302830))
# Combine date and time
combined = datetime.combine(date(2020,12,25), time(11,22,54))
print(combined)
# Formatting
print(combined.strftime("%Y-%m-%d %H:%M:%S"))

4.4 Timezone Conversion

from datetime import datetime, timezone, timedelta
utc_now = datetime.utcnow().replace(tzinfo=timezone.utc)
beijing = utc_now.astimezone(timezone(timedelta(hours=8)))
print(beijing)

5. Common Time Conversion Techniques

Timestamp to date.

Date to timestamp.

Formatting time.

Getting the current time in a specific format.

5.1 Timestamp to Date

import time
now_timestamp = time.time()
now_tuple = time.localtime(now_timestamp)
print(time.strftime("%Y/%m/%d %H:%M:%S", now_tuple))

5.2 Date to Timestamp

date_str = "2020-12-26 11:45:34"
date_array = time.strptime(date_str, "%Y-%m-%d %H:%M:%S")
print(time.mktime(date_array))

5.3 Reformatting Time

old = "2020-12-12 12:28:45"
arr = time.strptime(old, "%Y-%m-%d %H:%M:%S")
new = time.strftime("%Y%m%d-%H:%M:%S", arr)
print(new)

5.4 Getting Current Time in a Custom Format

import time
now = time.time()
now_tuple = time.localtime(now)
formatted = time.strftime("%Y/%m/%d %H:%M:%S", now_tuple)
print(formatted)

6. Summary

The article thoroughly introduces Python's three main modules for time output and conversion— calendar, time, and datetime —and summarizes four practical conversion tricks to help developers handle time data efficiently.