Python Archives - Page 710 of 827

How are deques in Python implemented, and when are they worse than lists?

August 13, 2022 by Magenaut

I’ve recently gotten into investigating how various data structures are implemented in Python in order to make my code more efficient. In investigating how lists and deques work, I found that I can get benefits when I want to shift and unshift reducing the time from O(n) in lists to O(1) in deques (lists being implemented as fixed-length arrays that have to be copied completely each time something is inserted at the front, etc…). What I can’t seem to find are the specifics of how a deque is implemented, and the specifics of its downsides v.s. lists. Can someone enlighten me on these two questions?

Python – Requests, Selenium – passing cookies while logging in

August 13, 2022 by Magenaut

I would like to integrate python Selenium and Requests modules to authenticate on a website.

How do I make a fixed size formatted string in python?

August 13, 2022 by Magenaut

10s format a string with 10 spaces, left justified by default

multiprocessing.Pool() slower than just using ordinary functions

August 13, 2022 by Magenaut

(This question is about how to make multiprocessing.Pool() run code faster. I finally solved it, and the final solution can be found at the bottom of the post.)

Binary random array with a specific proportion of ones?

August 13, 2022 by Magenaut

What is the efficient(probably vectorized with Matlab terminology) way to generate random number of zeros and ones with a specific proportion? Specially with Numpy?

Numpy: Creating a complex array from 2 real ones?

August 13, 2022 by Magenaut

I want to combine 2 parts of the same array to make a complex array:

How do you reload a Django model module using the interactive interpreter via “manage.py shell”?

August 13, 2022 by Magenaut

I know how to reload a regular Python module within a regular Python interpreter session. This question documents how to do that pretty well:

How can I save an image with PIL?

August 13, 2022 by Magenaut

I have just done some image processing using the Python image library (PIL) using a post I found earlier to perform fourier transforms of images and I can’t get the save function to work. The whole code works fine but it just wont save the resulting image:

Why is Python 3 not backwards compatible?

August 13, 2022 by Magenaut

Python 3.0, compared to 2.6. Python 3.0, also known as “Python 3000” or “Py3K”, is the first ever intentionally backwards incompatible Python release. There are more changes than in a typical release, and more that are important for all Python users. Nevertheless, after digesting the changes, you’ll find that Python really hasn’t changed all that much – by and large, we’re mostly fixing well-known annoyances and warts, and removing a lot of old cruft.

Python urllib2.urlopen() is slow, need a better way to read several urls

August 13, 2022 by Magenaut

As the title suggests, I’m working on a site written in python and it makes several calls to the urllib2 module to read websites. I then parse them with BeautifulSoup.