💡 Problem Formulation: When working with time in Python, you may need to convert time-related objects to milliseconds for precision or compatibility with systems that require time to be expressed in small units. This article describes how to convert various types of Python time objects to milliseconds. For instance, converting a datetime object of 2023-03-18 12:30:00 to its corresponding value in milliseconds.
Method 1: Using datetime and timestamp()
This technique involves converting a datetime object to a POSIX timestamp using the timestamp() method and then scaling the resultant float value to milliseconds by multiplying by 1,000.
Here’s an example:
from datetime import datetime # Create a datetime object dt = datetime(2023, 3, 18, 12, 30) # Convert to milliseconds milliseconds = int(dt.timestamp() * 1000) print(milliseconds)
Output:
1679135400000
This code snippet creates a datetime object corresponding to March 18, 2023, at 12:30 pm and then uses timestamp() to get the POSIX timestamp. The timestamp is then multiplied by 1,000 to convert it to milliseconds. Finally, the value is converted to an integer.
Method 2: Using time Module and time.time()
With the time module, you can get the current time in seconds since the epoch as a float, then multiply by 1,000 to get the current time in milliseconds.
Here’s an example:
import time # Current time in milliseconds current_time_milliseconds = int(round(time.time() * 1000)) print(current_time_milliseconds)
Output:
1679534805273
This code uses the time() function from the time module to get the current time since the epoch in seconds. The value is rounded and converted to milliseconds.
Method 3: Using time Module with time.gmtime() and Custom Conversion
A custom conversion function can be composed to convert the result of time.gmtime() to milliseconds by manually multiplying the components (hours, minutes, etc.) by their respective conversion factors.
Here’s an example:
import time
def to_milliseconds(tm):
millis = ((tm.tm_hour * 3600) + (tm.tm_min * 60) + tm.tm_sec) * 1000
return millis
# Convert current UTC time to milliseconds
current_utc_milliseconds = to_milliseconds(time.gmtime())
print(current_utc_milliseconds)Output:
47385000
The custom function to_milliseconds() takes a time struct as input and calculates the milliseconds by breaking down the hours, minutes, and seconds to their corresponding millisecond value.
Method 4: Using datetime Module with timedelta
The datetime module’s timedelta objects can represent time intervals, which can be converted to milliseconds by accessing its total_seconds() method and then converting to milliseconds.
Here’s an example:
from datetime import datetime, timedelta # Create a timedelta object td = timedelta(days=2, hours=3, minutes=4, seconds=5) # Convert to milliseconds milliseconds = int(td.total_seconds() * 1000) print(milliseconds)
Output:
180245000
This code snippet creates a timedelta object representing a time interval of 2 days, 3 hours, 4 minutes, and 5 seconds. The total seconds in this period are then multiplied by 1,000 to get the equivalent milliseconds.
Bonus One-Liner Method 5: Using List Comprehension with time.time_ns()
Python 3.7 introduces time.time_ns() which returns the current time in nanoseconds from the epoch. You can get milliseconds by dividing by 1,000,000. This one-liner uses a list comprehension for demonstration purposes.
Here’s an example:
import time # Current time in milliseconds using list comprehension current_time_milliseconds = [time.time_ns() // 1_000_000] print(current_time_milliseconds[0])
Output:
1679534805273
This one-liner uses the time_ns() function to get the current time in nanoseconds and directly converts it to milliseconds, demonstrating the power and conciseness of Python’s list comprehensions and underscored integer literals for readability.
Summary/Discussion
- Method 1: datetime.timestamp(). Strengths: Easy to use for converting specific datetime objects. Weaknesses: It is not suitable for current time or timedelta objects.
- Method 2: time.time(). Strengths: Ideal for getting the current time in milliseconds. Weaknesses: Less precision compared to time.time_ns().
- Method 3: Custom Conversion Function. Strengths: Mastery level control of time conversion. Weaknesses: More complex and prone to errors if not implemented correctly.
- Method 4: timedelta.total_seconds(). Strengths: Effective for timedelta objects. Weaknesses: Only works with timedelta, not datetime objects directly.
- Method 5: time.time_ns(). Strengths: Most precise and modern method. Weaknesses: Only available on Python 3.7 and later.