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Recursive lambda functions in C++11
...may make more sense:
std::function<int(int,int)> sum;
sum = [term,next,&sum](int a, int b)->int {
if(a>b)
return 0;
else
return term(a) + sum(next(a),b);
};
Obviously, this wouldn't work with auto. Recursive lambda functions work perfectly well (at least they do in MSVC, ...
How to deal with page breaks when printing a large HTML table
...t;
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Test</title>
<style type="text/css">
table { page-break-inside:auto }
tr { page-break-inside:avoid; page-break-after:auto }
thead { display:table-header-grou...
Sending an HTTP POST request on iOS
...
The following code describes a simple example using POST method.(How one can pass data by POST method)
Here, I describe how one can use of POST method.
1. Set post string with actual username and password.
NSString *post = [NSString stringWithFormat:@"User...
Rails: select unique values from a column
...rks only on "top level" queries, like above. Doesn't work on collection proxies ("has_many" relations, for example).
Address.distinct.pluck(:city) # => ['Moscow']
user.addresses.distinct.pluck(:city) # => ['Moscow', 'Moscow', 'Moscow']
In this case, deduplicate after the query
user.address...
How does having a dynamic variable affect performance?
...namic used as a parameter or rather those lines with dynamic behavior/context(?)
Here's the deal.
For every expression in your program that is of dynamic type, the compiler emits code that generates a single "dynamic call site object" that represents the operation. So, for example, if you have:
...
Pandas aggregate count distinct
...>>> df.groupby("date").agg({"duration": np.sum, "user_id": lambda x: x.nunique()})
duration user_id
date
2013-04-01 65 2
2013-04-02 45 1
share
...
Python: using a recursive algorithm as a generator
...
def getPermutations(string, prefix=""):
if len(string) == 1:
yield prefix + string
else:
for i in xrange(len(string)):
for perm in getPermutations(string[:i] + string[i+1:], prefix+string[i]):
yield perm
...
Generating a random password in php
...s 1):
function randomPassword() {
$alphabet = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890';
$pass = array(); //remember to declare $pass as an array
$alphaLength = strlen($alphabet) - 1; //put the length -1 in cache
for ($i = 0; $i < 8; $i++) {
$n = ra...
Why is transposing a matrix of 512x512 much slower than transposing a matrix of 513x513?
After conducting some experiments on square matrices of different sizes, a pattern came up. Invariably, transposing a matrix of size 2^n is slower than transposing one of size 2^n+1 . For small values of n , the difference is not major.
...
Combining two lists and removing duplicates, without removing duplicates in original list
...econd list has any duplicates of the first list ignored. .. A bit hard to explain, so let me show an example of what the code looks like, and what i want as a result.
...