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Retrieve only the queried element in an object array in MongoDB collection
...r to filter an array during projection, which has the benefit of including all matches, instead of just the first one.
db.test.aggregate([
// Get just the docs that contain a shapes element where color is 'red'
{$match: {'shapes.color': 'red'}},
{$project: {
shapes: {$filter: {
...
Why is  appearing in my HTML? [duplicate]
...acters using their actual codes.
Once you locate it, you can delete the small block of text around it and retype that text manually.
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Why use sprintf function in PHP?
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sprintf has all the formatting capabilities of the original printf which means you can do much more than just inserting variable values in strings.
For instance, specify number format (hex, decimal, octal), number of decimals, padding a...
django unit tests without a db
... doesn't require the db to set up. And while it is fast to setup a db, I really don't need it in some situations.
11 Answer...
JavaScript and Threads
...onBat JavaScript Benchmark (first link)
The Gears plugin can also be installed in Firefox.
Safari 4, and the WebKit nightlies have worker threads:
JavaScript Ray Tracer
Chrome has Gears baked in, so it can do threads, although it requires a confirmation prompt from the user (and it uses a d...
RegEx for Javascript to allow only alphanumeric
I need to find a reg ex that only allows alphanumeric. So far, everyone I try only works if the string is alphanumeric, meaning contains both a letter and a number. I just want one what would allow either and not require both.
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Swift 编程语言入门教程 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...Swift Programming Language》中摘录和提取而成。希望对各位的iOS&OSX开发有所帮助。今天在网上看到一篇非常好的教程，分享给大家
原文地址：http://gashero.iteye.com/blog/2075324
目录
1 简介
2 Swift入门
3 简单值
4 控制流
5 函...
Invert “if” statement to reduce nesting
...cked this code from the refactoring catalog. This specific refactoring is called: Replace Nested Conditional with Guard Clauses.
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What does Ruby have that Python doesn't, and vice versa?
There is a lot of discussions of Python vs Ruby, and I all find them completely unhelpful, because they all turn around why feature X sucks in language Y, or that claim language Y doesn't have X, although in fact it does. I also know exactly why I prefer Python, but that's also subjective, and would...
How to reshape data from long to wide format
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The reshape comments and similar argument names aren't all that helpful. However, I have found that for long to wide, you need to provide data = your data.frame, idvar = the variable that identifies your groups, v.names = the variables that will become multiple columns in wide f...