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What's the difference between lapply and do.call?
...r to map in other languages:
lapply returns a list of the same length as X, each element of which is the result of applying FUN to the corresponding element of X.
do.call constructs and executes a function call from a name or a function and a list of arguments to be passed to it.
Map applies a fun...
How to determine if a number is odd in JavaScript
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Use the bitwise AND operator.
function oddOrEven(x) {
return ( x & 1 ) ? "odd" : "even";
}
function checkNumber(argNumber) {
document.getElementById("result").innerHTML = "Number " + argNumber + " is " + oddOrEven(argNumber);
}
checkNumber(17);
<div i...
Python initializing a list of lists [duplicate]
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The problem is that they're all the same exact list in memory. When you use the [x]*n syntax, what you get is a list of n many x objects, but they're all references to the same object. They're not distinct instances, rather, just n references to the same instance.
T...
print memory address of Python variable [duplicate]
...d() returns the 'id' of a variable or object, but this doesn't return the expected 0x3357e182 style I was expecting to see for a memory address.
I want to do something like print &x , where x is a C++ int variable for example.
How can I do this in Python?
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Mac OS X安装Bochs - 更多技术 - 清泛网 - 专注C/C++及内核技术
Mac OS X安装Bochs1.安装x11;2.开启Mac OS X的root用户3.configure我在这里遇到的问题是，提示我少一个这个头文件X11 extensions Xrandr.h谷歌了一下，机子...1.安装x11;
2.开启Mac OS X的root用户
3.configure
我在这里遇到的问题是，提示我少一个...
Running V8 Javascript Engine Standalone
...shell.
Running the console:
$> ./v8-shell
V8 version 2.0.2
> var x = 10;
> x
10
> function foo(x) { return x * x; }
> foo
function foo(x) { return x * x; }
> quit()
Executing Javascript from the command line:
$> ./v8-shell -e 'print("10*10 = " + 10*10)'
10*10 = 100
Man...
What is an invariant?
The word seems to get used in a number of contexts. The best I can figure is that they mean a variable that can't change. Isn't that what constants/finals (darn you Java!) are for?
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“x not in y” or “not x in y”
...tor, which could be applied to a in b just as easily as any other boolean expression, whereas not in was a separate operator for convenience and clarity.
The disassembly above was revealing! It seems that while not obviously is a logical negation operator, the form not a in b is special cased so th...
How to filter by IP address in Wireshark?
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Match destination: ip.dst == x.x.x.x
Match source: ip.src == x.x.x.x
Match either: ip.addr == x.x.x.x
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How can I create a correlation matrix in R?
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An example,
d &lt- data.frame(x1=rnorm(10),
x2=rnorm(10),
x3=rnorm(10))
cor(d) # get correlations (returns matrix)
...