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Unique fields that allow nulls in Django
...o actually protect data integrity. Data may be entered via import scripts, from the shell, through an API or any other means. Much better to override the save() method than to make custom cases for every form that might touch the data.
– shacker
Jul 27 '16 at 1...
How to read a text file reversely with iterator in C#
...a large file, around 400K lines and 200 M. But sometimes I have to process from bottom up. How can I use iterator (yield return) here? Basically I don't like to load everything in memory. I know it is more efficient to use iterator in .NET.
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Abusing the algebra of algebraic data types - why does this work?
...in a moment.
As you've probably noticed, Haskell tends to borrow concepts from Category Theory, and all of the above has a very straightforward interpretation as such:
Given objects A and B in Hask, their product A×B is the unique (up to isomorphism) type that allows two projections fst : A×B ...
How do I convert a numpy array to (and display) an image?
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You could use PIL to create (and display) an image:
from PIL import Image
import numpy as np
w, h = 512, 512
data = np.zeros((h, w, 3), dtype=np.uint8)
data[0:256, 0:256] = [255, 0, 0] # red patch in upper left
img = Image.fromarray(data, 'RGB')
img.save('my.png')
img.show()
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Git: “Corrupt loose object”
Whenever I pull from my remote, I get the following error about compression. When I run the manual compression, I get the same:
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Get properties and values from unknown object
From the world of PHP I have decided to give C# a go. I've had a search but can't seem to find the answer of how to do the equivalent to this.
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How to replace all occurrences of a character in string?
...esn't contain such function but you could use stand-alone replace function from algorithm header.
#include <algorithm>
#include <string>
void some_func() {
std::string s = "example string";
std::replace( s.begin(), s.end(), 'x', 'y'); // replace all 'x' to 'y'
}
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Render HTML to PDF in Django site
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Try the solution from Reportlab.
Download it and install it as usual with python setup.py install
You will also need to install the following modules: xhtml2pdf, html5lib, pypdf with easy_install.
Here is an usage example:
First define th...
How to read data From *.CSV file using javascript?
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I was trying to read a .csv file from a mac. I was only able to get this script to recognize newline characters when I changed the first split to this var allTextLines = allText.split("\r"); After that it worked great! Thanks!
– Joe
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What is the difference between substr and substring?
... first argument, which can be negative for substr (in which case it starts from the end), but not for substring. See JefferMC answer, but it has so many less votes that a lot of people might miss this important part.
– youen
Jul 26 '17 at 19:46
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