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lodash multi-column sortBy descending

...ash 3.5.0 you can use sortByOrder (renamed orderBy in v4.3.0): var data = _.sortByOrder(array_of_objects, ['type','name'], [true, false]); Since version 3.10.0 you can even use standard semantics for ordering (asc, desc): var data = _.sortByOrder(array_of_objects, ['type','name'], ['asc', 'desc'...
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Is there a range class in C++11 for use with range based for loops?

...C++ standard library does not have one, but Boost.Range has boost::counting_range, which certainly qualifies. You could also use boost::irange, which is a bit more focused in scope. C++20's range library will allow you to do this via view::iota(start, end). ...
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Django 1.7 - makemigrations not detecting changes

... out) listed in the documentation: python manage.py makemigrations your_app_label The documentation does not make it obvious that you need to add the app label to the command, as the first thing it tells you to do is python manage.py makemigrations which will fail. The initial migration is don...
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Principal component analysis in Python

...is 2 x 20. Dropping the primes, d . Vt 2 principal vars = p.vars_pc( 20 vars ) U 1000 obs = p.pc_obs( 2 principal vars ) U . d . Vt 1000 obs, p.obs( 20 vars ) = pc_obs( vars_pc( vars )) fast approximate A . vars, using the `npc` principal components Ut ...
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How does functools partial do what it does?

...g like this (apart from keyword args support etc): def partial(func, *part_args): def wrapper(*extra_args): args = list(part_args) args.extend(extra_args) return func(*args) return wrapper So, by calling partial(sum2, 4) you create a new function (a callable, to b...
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How to log a method's execution time exactly in milliseconds?

... I just compared NSDate and mach_absolute_time() at around 30ms level. 27 vs. 29, 36 vs. 39, 43 vs. 45. NSDate was easier to use for me and the results were similar enough not to bother with mach_absolute_time(). – nevan king ...
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What is the “__v” field in Mongoose

I'm using Mongoose version 3 with MongoDB version 2.2. I've noticed a __v field has started appearing in my MongoDB documents. Is it something to do with versioning? How is it used? ...
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How to JSON serialize sets?

I have a Python set that contains objects with __hash__ and __eq__ methods in order to make certain no duplicates are included in the collection. ...
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Can “using” with more than one resource cause a resource leak?

...Drawing]System.Drawing.Font font4, [2] bool CS$4$0000 ) IL_0000: nop IL_0001: ldstr "Arial" IL_0006: ldc.r4 10 IL_000b: newobj instance void [System.Drawing]System.Drawing.Font::.ctor(string, float32) IL_0010: stloc.0 .try { IL_0011: ldstr "Arial" ...
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Should I use a class or dictionary?

...vantage? What happens if you later want to add some code? Where would your __init__ code go? Classes are for bundling related data (and usually code). Dictionaries are for storing key-value relationships, where usually the keys are all of the same type, and all the values are also of one type. Occ...