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Can dplyr package be used for conditional mutating?
...and the conditions (except for the default value of NA at the end) are mutually exclusive, as is the case in the question, then we can use an arithmetic expression such that each term is multiplied by the desired result using na_if at the end to replace 0 with NA.
df %>%
mutate(g = 2 * (a == 2 ...
How to add column if not exists on PostgreSQL?
...statement:
DO $$
BEGIN
BEGIN
ALTER TABLE <table_name> ADD COLUMN <column_name> <column_type>;
EXCEPTION
WHEN duplicate_column THEN RAISE NOTICE 'column <column_name> already exists in <table_name>.';
END;
END;
$$
...
iPhone: How to get current milliseconds?
... it like this: NSTimeInterval myInterval = NSDate.timeIntervalSince1970;// all those brackets are really old fashioned if you ask me.
– Pizzaiola Gorgonzola
Oct 2 '13 at 13:27
...
Get a CSS value with JavaScript
...
Somewhat off topic: some (all?) shorthand css properties are not accessible in JavaScript. E.g. you can get padding-left but not padding. JSFiddle
– David Winiecki
May 9 '14 at 21:10
...
Conditional HTML Attributes using Razor MVC3
...s" />
If strCSSClass is null then the class attribute won't render at all.
SSSHHH...don't tell. :)
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Use cases for NoSQL [closed]
NoSQL has been getting a lot of attention in our industry recently. I'm really interested in what peoples thoughts are on the best use-cases for its use over relational database storage. What should trigger a developer into thinking that particular datasets are more suited to a NoSQL solution. I'm p...
Setting up two different static directories in node.js Express framework
...nal (first) parameter to use() like so:
app.use("/public", express.static(__dirname + "/public"));
app.use("/public2", express.static(__dirname + "/public2"));
That way you get two different directories on the web that mirror your local directories, not one url path that fails over between two lo...
Interface defining a constructor signature?
...ult in Google some 7 years later, I thought I would chip in here - specifically to show how you could use an abstract base class in tandem with your existing Interface and maybe cut down on the amount of refactoring needed in the future for similar situations. This concept has already been hinted a...
Automatically add newline at end of curl response body
...or a curl request doesn't contain a trailing newline, I end up with this really annoying condition where the shell prompt is in the middle of the line, and escaping is messed up enough that when I put the last curl command on the screen, deleting characters from that curl command deletes the wrong c...
How to iterate for loop in reverse order in swift?
... an array with one trillion Ints!
Test:
var count = 0
for i in lazy(1...1_000_000_000_000).reverse() {
if ++count > 5 {
break
}
println(i)
}
For Swift 2.0 in Xcode 7:
for i in (1...10).reverse() {
print(i)
}
Note that in Swift 2.0, (1...1_000_000_000_000).reverse(...