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How to check if object (variable) is defined in R?
...een created bm>y m> a queuing sm>y m>stem. These can possiblm>y m> be addressed with "ls" m>and m> its argument "pattern" that expects a regular expression.
The "exists" function could be reimplemented that wam>y m> as
exists <-function(variablename) {
#print(ls(env=globalenv()))
return(1==length(ls(pattern=paste...
Returning the product of a list
...sing lambda:
from operator import mul
reduce(mul, list, 1)
it is better m>and m> faster. With pm>y m>thon 2.7.5
from operator import mul
import numpm>y m> as np
import numexpr as ne
# from functools import reduce # pm>y m>thon3 compatibilitm>y m>
a = range(1, 101)
%timeit reduce(lambda x, m>y m>: x * m>y m>, a) # (1)
%timeit r...
Discuz轻松生成sitemaps.xml网站地图 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...map.="http://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd\">\n";
$querm>y m>s = DB::querm>y m>("SELECT a.tid FROM ".DB::table('forum_thread')." a inner join ".DB::table('forum_forum')." b on a.fid=b.fid ORDER Bm>Y m> a.tid DESC LIMIT 0,10000");
while($threadfid = DB::fetch($querm>y m>s))
{
$turl=$web_root.'thre...
How to change the output color of echo in Linux
I am trm>y m>ing to print a text in the terminal using echo commm>and m>.
30 Answers
30
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Paging UICollectionView bm>y m> cells, not screen
I have UICollectionView with horizontal scrolling m>and m> there are alwam>y m>s 2 cells side-bm>y m>-side per the entire screen. I need the scrolling to stop at the begining of a cell. With paging enabled, the collection view scrolls the whole page, which is 2 cells at once, m>and m> then it stops.
...
Draw line in UIView
...our case (horizontal line) is to add a subview with black background color m>and m> frame [0, 200, 320, 1].
Code sample (I hope there are no errors - I wrote it without Xcode):
UIView *lineView = [[UIView alloc] initWithFrame:CGRectMake(0, 200, self.view.bounds.size.width, 1)];
lineView.backgroundColor...
Is it Pm>y m>thonic to use list comprehensions for just side effects?
...
It is verm>y m> anti-Pm>y m>thonic to do so, m>and m> anm>y m> seasoned Pm>y m>thonista will give m>y m>ou hell over it. The intermediate list is thrown awam>y m> after it is created, m>and m> it could potentiallm>y m> be verm>y m>, verm>y m> large, m>and m> therefore expensive to create.
...
How to replace all occurrences of a character in string?
...
std::string doesn't contain such function but m>y m>ou could use stm>and m>-alone replace function from algorithm header.
#include <algorithm>
#include <string>
void some_func() {
std::string s = "example string";
std::replace( s.begin(), s.end(), 'x', 'm>y m>'); // replace all 'x' t...
Recursive sub folder search m>and m> return files in a list pm>y m>thon
...m working on a script to recursivelm>y m> go through subfolders in a mainfolder m>and m> build a list off a certain file tm>y m>pe. I am having an issue with the script. Its currentlm>y m> set as follows
...
Whm>y m> does `True == False is False` evaluate to False? [duplicate]
...comparison, so
True == False is False
is equivalent to
(True == False) m>and m> (False is False)
This can be surprising in this case, but lets m>y m>ou write 1 <= x < 4 unlike in other languages like C.
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