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ReactJS: Modeling Bi-Directional Infinite Scrolling
... render them, it's really cheap to just allocate them and discard them. If 10k allocations is too big, you can instead pass a function that takes a range and return the elements.
<List>
{thousandelements.map(function() { return <Element /> })}
</List>
Your List component is ke...
Apply a function to every row of a matrix or a data frame
... 3 4
[3,] 5 6
R> apply(M, 1, function(x) 2*x[1]+x[2])
[1] 4 10 16
R>
This takes a matrix and applies a (silly) function to each row. You pass extra arguments to the function as fourth, fifth, ... arguments to apply().
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How can I do DNS lookups in Python, including referring to /etc/hosts?
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answered May 10 '10 at 18:36
Jochen RitzelJochen Ritzel
89.3k2525 gold badges181181 silver badges180180 bronze badges
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How to see if an object is an array without using reflection?
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edited Apr 27 '10 at 23:49
answered Apr 27 '10 at 23:26
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Programmatically find the number of cores on a machine
...CPU = sysinfo.dwNumberOfProcessors;
Linux, Solaris, AIX and Mac OS X >=10.4 (i.e. Tiger onwards)
int numCPU = sysconf(_SC_NPROCESSORS_ONLN);
FreeBSD, MacOS X, NetBSD, OpenBSD, etc.
int mib[4];
int numCPU;
std::size_t len = sizeof(numCPU);
/* set the mib for hw.ncpu */
mib[0] = CTL_HW;
mib[1...
How to check if a Ruby object is a Boolean
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answered Jun 13 '10 at 19:42
Konstantin HaaseKonstantin Haase
24.2k22 gold badges5252 silver badges5757 bronze badges
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How to validate date with format “mm/dd/yyyy” in JavaScript?
...rs
var parts = dateString.split("/");
var day = parseInt(parts[1], 10);
var month = parseInt(parts[0], 10);
var year = parseInt(parts[2], 10);
// Check the ranges of month and year
if(year < 1000 || year > 3000 || month == 0 || month > 12)
return false;
...
To ternary or not to ternary? [closed]
...
Use it for simple expressions only:
int a = (b > 10) ? c : d;
Don't chain or nest ternary operators as it hard to read and confusing:
int a = b > 10 ? c < 20 ? 50 : 80 : e == 2 ? 4 : 8;
Moreover, when using ternary operator, consider formatting the code in a way ...
How can I check if an ip is in a network in Python?
...t == net
address = dottedQuadToNum("192.168.1.1")
networka = networkMask("10.0.0.0",24)
networkb = networkMask("192.168.0.0",24)
print (address,networka,networkb)
print addressInNetwork(address,networka)
print addressInNetwork(address,networkb)
This outputs:
False
True
If you just want a singl...
Using 'starts with' selector on individual class names
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answered Feb 1 '10 at 17:01
Josh StodolaJosh Stodola
76.3k4242 gold badges177177 silver badges220220 bronze badges
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