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Best practices for circular shift (rotate) operations in C++
...otate question with some more details about what asm gcc/clang produce for x86.
The most compiler-friendly way to express a rotate in C and C++ that avoids any Undefined Behaviour seems to be John Regehr's implementation. I've adapted it to rotate by the width of the type (using fixed-width types ...
javascript set a variable if undefined
...f the variable is strictly undefined then the safest way is to write:
var x = (typeof x === 'undefined') ? your_default_value : x;
On newer browsers it's actually safe to write:
var x = (x === undefined) ? your_default_value : x;
but be aware that it is possible to subvert this on older browse...
How to avoid warning when introducing NAs by coercion
...
Use suppressWarnings():
suppressWarnings(as.numeric(c("1", "2", "X")))
[1] 1 2 NA
This suppresses warnings.
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Convert Int to String in Swift
...
Converting Int to String:
let x : Int = 42
var myString = String(x)
And the other way around - converting String to Int:
let myString : String = "42"
let x: Int? = myString.toInt()
if (x != nil) {
// Successfully converted String to Int
}
Or if ...
In php, is 0 treated as empty?
Code will explain more:
18 Answers
18
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pyplot axes labels for subplots
...hen set the common labels.
import random
import matplotlib.pyplot as plt
x = range(1, 101)
y1 = [random.randint(1, 100) for _ in xrange(len(x))]
y2 = [random.randint(1, 100) for _ in xrange(len(x))]
fig = plt.figure()
ax = fig.add_subplot(111) # The big subplot
ax1 = fig.add_subplot(211)
ax2 =...
X-Frame-Options Allow-From multiple domains
I have an ASP.NET 4.0 IIS7.5 site which I need secured using the X-Frame-Options header.
11 Answers
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Drop data frame columns by name
...
You can use a simple list of names :
DF <- data.frame(
x=1:10,
y=10:1,
z=rep(5,10),
a=11:20
)
drops <- c("x","z")
DF[ , !(names(DF) %in% drops)]
Or, alternatively, you can make a list of those to keep and refer to them by name :
keeps <- c("y", "a")
DF[keeps]
EDI...
Tricks to manage the available memory in an R session
...em. But by far the most effective solution was ... to run under 64-bit Linux with ample memory.
27 Answers
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