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What's the u prefix in a Python string?
...l's Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!) essay on character sets.
Q: sry no time code pls
A: Fine. try str('Some String') or 'Some String'.encode('ascii', 'ignore'). But you should really read some of the answers ...
Difference between numpy.array shape (R, 1) and (R,)
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1. The meaning of shapes in NumPy
You write, "I know literally it's list of numbers and list of lists where all list contains only a number" but that's a bit of an unhelpful way to think about it.
The best way to think about NumPy arrays is that they consist of two parts, ...
HashSet versus Dictionary w.r.t searching time to find if an item exists
...P. I already have a dictionary i'm using for other reasons, and wanted to know if i benefit from changing to a Hashset instead of using ContainsKey. Looks like the answer is no since both are so fast.
– FistOfFury
Sep 12 '12 at 19:15
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Which characters are valid in CSS class names/selectors?
What characters/symbols are allowed within the CSS class selectors?
I know that the following characters are invalid , but what characters are valid ?
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What is android:weightSum in android, and how does it work?
I want to know: What is android:weightSum and layout weight, and how do they work?
9 Answers
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List comprehension rebinds names even after scope of comprehension. Is this right?
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Also note that now in 2.7, set and dictionary comprehensions (and generators) have private scopes, but list comprehensions still don't. While this makes some sense in that the former were all back-ported from Python 3, it really makes the c...
Maven2: Missing artifact but jars are in place
From now to then, my Maven 2 started to mess around.
33 Answers
33
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Sort rows in data.table in decreasing order on string key `order(-x,v)` gives error on data.table 1.
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Update
data.table v1.9.6+ now supports OP's original attempt and the following answer is no longer necessary.
You can use DT[order(-rank(x), y)].
x y v
1: c 1 7
2: c 3 8
3: c 6 9
4: b 1 1
5: b 3 2
6: b 6 3
7: a 1 4
8: a 3 5
9: a 6 6
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How to write a simple database engine [closed]
...ed in learning how a database engine works (i.e. the internals of it). I know most of the basic data structures taught in CS (trees, hash tables, lists, etc.) as well as a pretty good understanding of compiler theory (and have implemented a very simple interpreter) but I don't understand how to go ...
moving committed (but not pushed) changes to a new branch after pull
... (the current branch) without switching the current branch to new-work. So now new-work contains all the new commits. Then the reset moves the current branch (still master) back to origin/master.
– Mark Longair
Jan 21 '15 at 22:01
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