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The order of elements in Dictionary
... For purposes of enumeration, each item in the dictionary is treated as a KeyValuePair<TKey, TValue> structure representing a value and its key. The order in which the items are returned is undefined.
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Why does substring slicing with index out of range work?
...t-ins) doesn't cause an error.
It might be surprising at first, but it makes sense when you think about it. Indexing returns a single item, but slicing returns a subsequence of items. So when you try to index a nonexistent value, there's nothing to return. But when you slice a sequence outside of ...
In Python, how do I iterate over a dictionary in sorted key order?
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Haven't tested this very extensively, but works in Python 2.5.2.
>>> d = {"x":2, "h":15, "a":2222}
>>> it = iter(sorted(d.iteritems()))
>>> it.next()
('a', 2222)
>>> it.next()
('h', 15)
>>> it.next()
('x', 2)
>>>
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How to use sidebar with the keyboard in Sublime Text 2 and 3?
...to navigate thru files/folders in our projects. For that we can use the hotkey ctrl+k ctrl+b (in windows).
13 Answers
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Remove duplicate values from JS array [duplicate]
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Quick and dirty using jQuery:
var names = ["Mike","Matt","Nancy","Adam","Jenny","Nancy","Carl"];
var uniqueNames = [];
$.each(names, function(i, el){
if($.inArray(el, uniqueNames) === -1) uniqueNames.push(el);
});
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How to add an extra column to a NumPy array
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I think a more straightforward solution and faster to boot is to do the following:
import numpy as np
N = 10
a = np.random.rand(N,N)
b = np.zeros((N,N+1))
b[:,:-1] = a
And timings:
In [23]: N = 10
In [24]: a = np.random.rand(N...
Define all functions in one .R file, call them from another .R file. How, if possible?
... by source("xyz.R") (assuming that both these files are in your current working directory.
If abc.R is:
fooABC <- function(x) {
k <- x+1
return(k)
}
and xyz.R is:
fooXYZ <- function(x) {
k <- fooABC(x)+1
return(k)
}
then this will work:
> source("abc.R")
> s...
How is set() implemented?
I've seen people say that set objects in python have O(1) membership-checking. How are they implemented internally to allow this? What sort of data structure does it use? What other implications does that implementation have?
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delete map[key] in go?
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Strangely enough,
package main
func main () {
var sessions = map[string] chan int{};
delete(sessions, "moo");
}
seems to work. This seems a poor use of resources though!
Another way is to check for existence and use the value itself:
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How do I determine k when using k-means clustering?
I've been studying about k-means clustering , and one thing that's not clear is how you choose the value of k. Is it just a matter of trial and error, or is there more to it?
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