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Objective-C and Swift URL encoding
...*)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(
NULL,
(__bridge CFStringRef) unescaped,
NULL,
CFSTR("!*'();:@&=+$,/?%#[]\" "),
kCFStringEncodingUTF8));
Using Core Foundation Without ARC:
NSString *escapedString = (NSString *)CFURLCreateStringByAddingPercentEs...
How to filter array in subdocument with MongoDB [duplicate]
...use $group to put it back together:
db.test.aggregate([
{ $match: {_id: ObjectId("512e28984815cbfcb21646a7")}},
{ $unwind: '$list'},
{ $match: {'list.a': {$gt: 3}}},
{ $group: {_id: '$_id', list: {$push: '$list.a'}}}
])
outputs:
{
"result": [
{
"_id": ObjectId("512...
do N times (declarative syntax)
...s 2017, you may use ES6:
[1,2,3].forEach(i => Array(i).fill(i).forEach(_ => {
something()
}))
or in good old ES5:
[1,2,3].forEach(function(i) {
Array(i).fill(i).forEach(function() {
something()
})
}))
In both cases, the outpout will be
The outpout will be
something
somethin...
When and why should I use a namedtuple instead of a dictionary? [duplicate]
... to create a bunch of instances of a class like:
class Container:
def __init__(self, name, date, foo, bar):
self.name = name
self.date = date
self.foo = foo
self.bar = bar
mycontainer = Container(name, date, foo, bar)
and not change the attributes after you se...
Rails Root directory path?
...
which returns a Pathname object. If you want a string you have to add .to_s. If you want another path in your Rails app, you can use join like this:
Rails.root.join('app', 'assets', 'images', 'logo.png')
In Rails 2 you can use the RAILS_ROOT constant, which is a string.
...
Get Image size WITHOUT loading image into memory
... data (or call the load method).
Digging deeper, we see that .open calls _open which is a image-format specific overload. Each of the implementations to _open can be found in a new file, eg. .jpeg files are in JpegImagePlugin.py. Let's look at that one in depth.
Here things seem to get a bit tric...
Convert a row of a data frame to vector
...u have to be careful if your row contains a factor. Here is an example:
df_1 = data.frame(V1 = factor(11:15),
V2 = 21:25)
df_1[1,] %>% as.numeric() # you expect 11 21 but it returns
[1] 1 21
Here is another example (by default data.frame() converts characters to factors)
d...
Is bool a native C type?
...ent C - C99, but not in C89/90.
In C99 the native type is actually called _Bool, while bool is a standard library macro defined in stdbool.h (which expectedly resolves to _Bool). Objects of type _Bool hold either 0 or 1, while true and false are also macros from stdbool.h.
Note, BTW, that this imp...
Why is parenthesis in print voluntary in Python 2.7?
...*This print behavior in Python 2 can be changed to that of Python 3:
from __future__ import print_function
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Best algorithm for detecting cycles in a directed graph [closed]
...e following Wikipedia article:
http://en.wikipedia.org/wiki/Topological_sorting
has the pseudo-code for one algorithm, and a brief description of another from Tarjan. Both have O(|V| + |E|) time complexity.
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