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How exactly do Django content types work?
...Blah blah, let's dive into some code and see what I mean.
# ourapp.models
from django.conf import settings
from django.db import models
# Assign the User model in case it has been "swapped"
User = settings.AUTH_USER_MODEL
# Create your models here
class Post(models.Model):
author = models.Forei...
Why are dates calculated from January 1st, 1970?
...ing is standard.
Two Dozen Epochs
Time in computing is not always tracked from the beginning of 1970 UTC. While that epoch reference is popular, various computing environments over the decades have used at least nearly two dozen epochs. Some are from other centuries. They range from year 0 (zero) t...
python generator “send” function purpose?
...ite coroutines
def coroutine():
for i in range(1, 10):
print("From generator {}".format((yield i)))
c = coroutine()
c.send(None)
try:
while True:
print("From user {}".format(c.send(1)))
except StopIteration: pass
prints
From generator 1
From user 2
From generator 1
From u...
How to convert R Markdown to PDF?
...g.,
render("input.Rmd", "pdf_document")
Command-line:
When I run render from the command-line (e.g., using a makefile), I sometimes have issues with pandoc not being found. Presumably, it is not on the search path.
The following answer explains how to add pandoc to the R environment.
So for exam...
What's the difference between dependencies, devDependencies and peerDependencies in npm package.json
... behavior differences:
dependencies are installed on both:
npm install from a directory that contains package.json
npm install $package on any other directory
devDependencies are:
also installed on npm install on a directory that contains package.json, unless you pass the --production flag (g...
What is the difference between bottom-up and top-down?
...pically, you would perform a recursive call (or some iterative equivalent) from the root, and either hope you will get close to the optimal evaluation order, or obtain a proof that you will help you arrive at the optimal evaluation order. You would ensure that the recursive call never recomputes a s...
ImportError: No module named PIL
...rsions of) PIL.
You can get more information about how to use this module from the official tutorial.
PS: In fact, on some installs, import PIL does work, which adds to the confusion. This is confirmed by an example from the documentation, as @JanneKarila found out, and also by some more recent ve...
How do you split a list into evenly sized chunks?
...unks you want:
def chunks(lst, n):
"""Yield successive n-sized chunks from lst."""
for i in range(0, len(lst), n):
yield lst[i:i + n]
import pprint
pprint.pprint(list(chunks(range(10, 75), 10)))
[[10, 11, 12, 13, 14, 15, 16, 17, 18, 19],
[20, 21, 22, 23, 24, 25, 26, 27, 28, 29]...
Java NIO FileChannel versus FileOutputstream performance / usefulness
...ing obvious bottlenecks, which I suggest your micro-benchmark might suffer from. Potential areas for investigating:
The buffer size. The algorithm you basically have is
copy from disk to buffer
copy from buffer to disk
My own experience has been that this buffer size is ripe for tuning. I've...
The case against checked exceptions
...spect Goslings motivation for not putting operator overrides in Java comes from a similar argument - they confuse the programmer because they are often abused.
But in the end, I find it a bogus argument of Hejlsberg's and possibly a post-hoc one created to explain the lack rather than a well though...