Formatting Date and Time in Python
Formatting Date and Time in Python
Python provides powerful formatting options for dates and times using the strftime() method and parsing using strptime() method.
from datetime import *
# Create a datetime object for 2010, January 1st at 10:20:30
dt1 = datetime(2010, 1, 1, 10, 20, 30)
# Display the datetime object (output shown in the image)
# datetime.datetime(2010, 1, 1, 10, 20, 30)
# Format the datetime object using specific directives
dt1.strftime('%d %B, %A %Y. %H:%M:%S')
# Format the datetime object using alternative directives
dt1.strftime('%-d %b, %a %y. %H:%M:%S')# The string to be converted
str1 = '10 Jan 2015, 10:15:30'
# Check the type of the variable (output shown in the image)
# type(str1)
# <class 'str'>
# Convert the string (str1) into a datetime object (dt2)
# The format string ('%d %b %Y, %H:%M:%S') exactly matches the structure of str1
dt2 = datetime.strptime(str1, '%d %b %Y, %H:%M:%S')
# Display the resulting datetime object (output shown in the image)
# datetime.datetime(2015, 1, 10, 10, 15, 30)1. Basic Formatting with strftime()
Date Formatting
python
from datetime import date, datetime
# Current date
today = date.today()
print("Date Formatting Examples:")
print(f"Default: {today}")
print(f"YYYY-MM-DD: {today.strftime('%Y-%m-%d')}")
print(f"MM/DD/YYYY: {today.strftime('%m/%d/%Y')}")
print(f"DD-MM-YYYY: {today.strftime('%d-%m-%Y')}")
print(f"Full month: {today.strftime('%B %d, %Y')}")
print(f"Abbr month: {today.strftime('%b %d, %Y')}")
print(f"Day name: {today.strftime('%A, %B %d, %Y')}")
# Output:
# Default: 2023-12-25
# YYYY-MM-DD: 2023-12-25
# MM/DD/YYYY: 12/25/2023
# DD-MM-YYYY: 25-12-2023
# Full month: December 25, 2023
# Abbr month: Dec 25, 2023
# Day name: Monday, December 25, 2023
Time Formatting
python
from datetime import time, datetime
# Current time
now = datetime.now().time()
print("\nTime Formatting Examples:")
print(f"24-hour: {now.strftime('%H:%M:%S')}")
print(f"12-hour: {now.strftime('%I:%M:%S %p')}")
print(f"Short time: {now.strftime('%I:%M %p')}")
print(f"With milliseconds: {now.strftime('%H:%M:%S.%f')}")
# Output:
# 24-hour: 14:30:45
# 12-hour: 02:30:45 PM
# Short time: 02:30 PM
# With milliseconds: 14:30:45.123456
DateTime Formatting
python
from datetime import datetime
current_dt = datetime.now()
print("\nDateTime Formatting Examples:")
print(f"Full: {current_dt.strftime('%Y-%m-%d %H:%M:%S')}")
print(f"Readable: {current_dt.strftime('%A, %B %d, %Y at %I:%M %p')}")
print(f"File friendly: {current_dt.strftime('%Y%m%d_%H%M%S')}")
print(f"SQL format: {current_dt.strftime('%Y-%m-%d %H:%M:%S')}")
print(f"US format: {current_dt.strftime('%m/%d/%Y %I:%M %p')}")
print(f"EU format: {current_dt.strftime('%d/%m/%Y %H:%M')}")
# Output:
# Full: 2023-12-25 14:30:45
# Readable: Monday, December 25, 2023 at 02:30 PM
# File friendly: 20231225_143045
# SQL format: 2023-12-25 14:30:45
# US format: 12/25/2023 02:30 PM
# EU format: 25/12/2023 14:30
2. Common Format Codes
| Code | Meaning | Example |
|---|---|---|
%Y | Year with century | 2023 |
%y | Year without century | 23 |
%m | Month (01-12) | 12 |
%B | Full month name | December |
%b | Abbreviated month | Dec |
%d | Day of month (01-31) | 25 |
%A | Full weekday name | Monday |
%a | Abbreviated weekday | Mon |
%H | Hour (00-23) | 14 |
%I | Hour (01-12) | 02 |
%M | Minute (00-59) | 30 |
%S | Second (00-59) | 45 |
%f | Microsecond | 123456 |
%p | AM/PM | PM |
%j | Day of year (001-366) | 359 |
3. Practical Formatting Examples
Logging Format
python
from datetime import datetime
def log_message(level, message):
timestamp = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
print(f"[{timestamp}] [{level.upper()}] {message}")
# Usage
log_message("info", "Application started")
log_message("error", "Database connection failed")
log_message("warning", "Low disk space")
# Output:
# [2023-12-25 14:30:45] [INFO] Application started
# [2023-12-25 14:30:46] [ERROR] Database connection failed
# [2023-12-25 14:30:47] [WARNING] Low disk space
File Naming Convention
python
from datetime import datetime
def generate_filename(prefix, extension="txt"):
timestamp = datetime.now().strftime('%Y%m%d_%H%M%S')
return f"{prefix}_{timestamp}.{extension}"
# Usage
files = [
generate_filename("report"),
generate_filename("backup", "zip"),
generate_filename("log", "log")
]
for file in files:
print(f"Generated: {file}")
# Output:
# Generated: report_20231225_143045.txt
# Generated: backup_20231225_143045.zip
# Generated: log_20231225_143045.log
User-Friendly Display
python
from datetime import datetime, timedelta
def format_relative_time(dt):
now = datetime.now()
diff = now - dt
if diff.days == 0:
if diff.seconds < 60:
return "Just now"
elif diff.seconds < 3600:
return f"{diff.seconds // 60} minutes ago"
else:
return f"{diff.seconds // 3600} hours ago"
elif diff.days == 1:
return "Yesterday"
elif diff.days < 7:
return f"{diff.days} days ago"
else:
return dt.strftime('%B %d, %Y')
# Test with different times
test_times = [
datetime.now() - timedelta(minutes=5),
datetime.now() - timedelta(hours=2),
datetime.now() - timedelta(days=1),
datetime.now() - timedelta(days=3),
datetime.now() - timedelta(days=10)
]
print("Relative Time Formatting:")
for time in test_times:
formatted = format_relative_time(time)
print(f"{time} -> {formatted}")
4. Parsing Strings with strptime()
Basic Parsing
python
from datetime import datetime
# Parse different date formats
date_strings = [
"2023-12-25",
"12/25/2023",
"25-12-2023 14:30:45",
"December 25, 2023",
"25 Dec 2023 02:30 PM"
]
formats = [
'%Y-%m-%d',
'%m/%d/%Y',
'%d-%m-%Y %H:%M:%S',
'%B %d, %Y',
'%d %b %Y %I:%M %p'
]
print("String to DateTime Parsing:")
for date_str, fmt in zip(date_strings, formats):
parsed_dt = datetime.strptime(date_str, fmt)
print(f"'{date_str}' -> {parsed_dt}")
Advanced Parsing Examples
python
from datetime import datetime
def parse_flexible_date(date_string):
"""Try multiple date formats"""
formats = [
'%Y-%m-%d',
'%m/%d/%Y',
'%d-%m-%Y',
'%B %d, %Y',
'%b %d, %Y',
'%Y%m%d',
'%d/%m/%Y %H:%M:%S',
'%m/%d/%Y %I:%M %p'
]
for fmt in formats:
try:
return datetime.strptime(date_string, fmt)
except ValueError:
continue
raise ValueError(f"Unable to parse date: {date_string}")
# Test with various date strings
test_dates = [
"2023-12-25",
"12/25/2023",
"25-12-2023",
"December 25, 2023",
"Dec 25, 2023",
"20231225",
"25/12/2023 14:30:45",
"12/25/2023 02:30 PM"
]
print("Flexible Date Parsing:")
for date_str in test_dates:
try:
parsed = parse_flexible_date(date_str)
print(f"✓ '{date_str}' -> {parsed}")
except ValueError as e:
print(f"✗ {e}")
5. Custom Formatting Functions
Multi-language Date Formatting
python
from datetime import datetime
class DateFormatter:
def __init__(self, language='en'):
self.language = language
self.months_en = {
1: 'January', 2: 'February', 3: 'March', 4: 'April',
5: 'May', 6: 'June', 7: 'July', 8: 'August',
9: 'September', 10: 'October', 11: 'November', 12: 'December'
}
self.months_es = {
1: 'Enero', 2: 'Febrero', 3: 'Marzo', 4: 'Abril',
5: 'Mayo', 6: 'Junio', 7: 'Julio', 8: 'Agosto',
9: 'Septiembre', 10: 'Octubre', 11: 'Noviembre', 12: 'Diciembre'
}
def format_custom(self, dt, format_type='long'):
if self.language == 'en':
months = self.months_en
else:
months = self.months_es
if format_type == 'long':
return f"{months[dt.month]} {dt.day}, {dt.year}"
elif format_type == 'short':
return f"{dt.month}/{dt.day}/{dt.year}"
elif format_type == 'numeric':
return f"{dt.year}-{dt.month:02d}-{dt.day:02d}"
# Usage
formatter_en = DateFormatter('en')
formatter_es = DateFormatter('es')
current_dt = datetime.now()
print("Multi-language Formatting:")
print(f"English long: {formatter_en.format_custom(current_dt, 'long')}")
print(f"Spanish long: {formatter_es.format_custom(current_dt, 'long')}")
print(f"Short: {formatter_en.format_custom(current_dt, 'short')}")
print(f"Numeric: {formatter_en.format_custom(current_dt, 'numeric')}")
Template-based Formatting
python
from datetime import datetime
import re
class TemplateFormatter:
def __init__(self):
self.templates = {
'log': '[{date} {time}] {message}',
'file': '{prefix}_{date}_{time}.{ext}',
'display': 'Today is {weekday}, {month} {day}, {year}',
'sql': '{year}-{month:02d}-{day:02d} {hour:02d}:{minute:02d}:{second:02d}'
}
def format(self, template_name, dt, **kwargs):
template = self.templates.get(template_name)
if not template:
raise ValueError(f"Unknown template: {template_name}")
# Extract date components
components = {
'date': dt.strftime('%Y-%m-%d'),
'time': dt.strftime('%H:%M:%S'),
'year': dt.year,
'month': dt.month,
'day': dt.day,
'hour': dt.hour,
'minute': dt.minute,
'second': dt.second,
'weekday': dt.strftime('%A'),
'month_name': dt.strftime('%B')
}
# Add custom kwargs
components.update(kwargs)
# Format the template
return template.format(**components)
# Usage
formatter = TemplateFormatter()
current_dt = datetime.now()
print("Template-based Formatting:")
print(formatter.format('log', current_dt, message='System started'))
print(formatter.format('file', current_dt, prefix='backup', ext='zip'))
print(formatter.format('display', current_dt))
print(formatter.format('sql', current_dt))
6. Complete Example: Event Formatter
python
from datetime import datetime, timedelta
class EventFormatter:
@staticmethod
def format_event_summary(event_name, start_dt, end_dt):
"""Format event information in a user-friendly way"""
# Date formatting
if start_dt.date() == end_dt.date():
# Same day event
date_str = start_dt.strftime('%A, %B %d, %Y')
time_str = f"{start_dt.strftime('%I:%M %p')} - {end_dt.strftime('%I:%M %p')}"
else:
# Multi-day event
date_str = f"{start_dt.strftime('%b %d')} to {end_dt.strftime('%b %d, %Y')}"
time_str = f"Starts: {start_dt.strftime('%I:%M %p')}"
# Duration
duration = end_dt - start_dt
hours = duration.total_seconds() / 3600
return f"""
Event: {event_name}
Date: {date_str}
Time: {time_str}
Duration: {hours:.1f} hours
"""
@staticmethod
def format_calendar_entry(event_name, dt, reminder_minutes=0):
"""Format for calendar applications"""
reminder_time = dt - timedelta(minutes=reminder_minutes)
return f"""
BEGIN:VEVENT
SUMMARY:{event_name}
DTSTART:{dt.strftime('%Y%m%dT%H%M%S')}
DTEND:{(dt + timedelta(hours=1)).strftime('%Y%m%dT%H%M%S')}
REMINDER:{reminder_time.strftime('%Y%m%dT%H%M%S')}
END:VEVENT
""".strip()
# Usage
event_formatter = EventFormatter()
# Create test events
meeting_start = datetime(2023, 12, 26, 14, 0, 0)
meeting_end = datetime(2023, 12, 26, 15, 30, 0)
conference_start = datetime(2023, 12, 27, 9, 0, 0)
conference_end = datetime(2023, 12, 28, 17, 0, 0)
print("Event Formatting Examples:")
print(event_formatter.format_event_summary("Team Meeting", meeting_start, meeting_end))
print(event_formatter.format_event_summary("Tech Conference", conference_start, conference_end))
print(event_formatter.format_calendar_entry("Team Meeting", meeting_start, 15))
Key Takeaways:
- Use
strftime()to convert datetime objects to formatted strings - Use
strptime()to convert formatted strings to datetime objects - Learn common format codes like
%Y,%m,%d,%H,%M,%S - Create custom formatters for specific application needs
- Handle multiple formats when parsing user input
These formatting techniques are essential for displaying dates and times in user-friendly ways and for parsing date strings from various sources!
