Author: John Au-Yeung

Sometimes, we want to trim whitespace from a string with Python.

In this article, we’ll look at how to trim whitespace from a string with Python.

How to trim whitespace from a string with Python?

To trim whitespace from a string with Python, we can use the Python string’s strip method.

For instance, we write:

stripped = ' Hello '.strip()
print(stripped)

to remove the leading and trailing whitespaces from the ' Hello ' string.

Therefore, stripped is 'Hello'.

Conclusion

To trim whitespace from a string with Python, we can use the Python string’s strip method.

Sometimes, we want to check for NaN values with Python.

In this article, we’ll look at how to check for NaN values with Python.

How to check for NaN values with Python?

To check for NaN values with Python, we can use the math.isnan method.

For instance, we write:

import math

x = float('nan')
isnan = math.isnan(x)
print(isnan)

We call float with a non-number string and assign that to x.

Then we call math.isnan with x to check if x is NaN or not and assign the returned result to isnan.

Therefore, isnan is True since x is not a number.

Conclusion

To check for NaN values with Python, we can use the math.isnan method.

Sometimes, we want to check if a directory exists in Python.

In this article, we’ll look at how to check if a directory exists in Python.

How to check if a directory exists in Python?

To check if a directory exists in Python, we can use the os.path.isdir or os.path.exists methods.

For instance, we write:

import os

isdir = os.path.isdir('new_folder')
print(isdir)

We pass in the path string to check if whether the directory with the given path exists.

isdir is True if the folder exists at the given path. Otherwise, it’s False.

To use os.path.exists, we write:

import os

isdir = os.path.exists(os.path.join(os.getcwd(), 'new_folder'))
print(isdir)

We call os.path.exists with the path created with os.path.join that joins the path segments together.

os.getcwd() returns the path of the current working directory.

isdir is True if the folder exists at the given path. Otherwise, it’s False.

Conclusion

To check if a directory exists in Python, we can use the os.path.isdir or os.path.exists methods.

Sometimes, we want to check which version of Python is running in a script.

In this article, we’ll look at how to check which version of Python is running in a script.

How to check which version of Python is running in a script?

To check which version of Python is running in a script, we can use the sys.version and sys.version_info properties.

For instance, we write:

import sys

print(sys.version)
print(sys.version_info)

sys.version provides basic version info.

And it returns data like:

3.8.12 (default, Sep 10 2021, 00:16:05) 
[GCC 7.5.0]

sys.version_info provides more detailed version info.

It returns data like:

sys.version_info(major=3, minor=8, micro=12, releaselevel='final', serial=0)

Conclusion

To check which version of Python is running in a script, we can use the sys.version and sys.version_info properties.

Sometimes, we want to use threading in Python.

In this article, we’ll look at how to use threading in Python.

How to use threading in Python?

To use threading in Python, we can use the Pool class from the multiprocessing.dummy module.

For instance, we write:

import urllib.request
from multiprocessing.dummy import Pool as ThreadPool

urls = [
    'http://www.python.org', 'http://www.python.org/about/',
    'http://www.onlamp.com/pub/a/python/2003/04/17/metaclasses.html',
    'http://www.python.org/doc/', 'http://www.python.org/getit/'
]

pool = ThreadPool(4)
results = pool.map(urllib.request.urlopen, urls)
pool.close()
pool.join()

We import the Pool class as ThreadPool.

Then we create a thread pool with 4 worker threads in it with the ThreadPool class.

Next, we call pool.map with the urllib.request.urlopen function and urls to call urllib.request.urlopen with the entries in urls and return the results.

Then we call pool.close to close the pool and wait for the work to finish with pool.join.

Conclusion

To use threading in Python, we can use the Pool class from the multiprocessing.dummy module.