How to parse a yaml file into ruby hashs and/or arrays?
I would use something like: hash = YAML.load(File.read(“file_path”))
hash
How to force a page to reload if all what was changed in url is hash?
Remove the anchor you’re going to navigate to, then use approach #2? Since there’s no anchor, setting the hash shouldn’t scroll the page.
Hashing 2D, 3D and nD vectors
There’s a spatial hash function described in Optimized Spatial Hashing for Collision Detection of Deformable Objects. They use the hash function hash(x,y,z) = ( x p1 xor y p2 xor z p3) mod n where p1, p2, p3 are large prime numbers, in our case 73856093, 19349663, 83492791, respectively. The value n is the hash … Read more
Where can I find source or algorithm of Python’s hash() function?
If you download the source code of Python, you will find it for sure! But bear in mind the hash function is implemented for each kind of objects differently. For example, you will find the unicode hash function in Objects/unicodeobject.c in the function unicode_hash. You might have to look a bit more to find the … Read more
What is the best way to implement this composite GetHashCode()
Like described by Jon Skeet in this SO answer, it is best practice to pick some prime numbers and multiply these with the single hash codes, then sum everything up. public int GetHashCode() { unchecked { int hash = 17; // Maybe nullity checks, if these are objects not primitives! hash = hash * 23 … Read more
How can I initialize an Array inside a Hash in Ruby [duplicate]
@my_hash = Hash.new(Array.new) This creates exactly one array object, which is returned every time a key is not found. Since you only ever mutate that array and never create a new one, all your keys map to the same array. What you want to do is: @my_hash = Hash.new {|h,k| h[k] = Array.new } or … Read more
C# Why can equal decimals produce unequal hash values?
To start with, C# isn’t doing anything wrong at all. This is a framework bug. It does indeed look like a bug though – basically whatever normalization is involved in comparing for equality ought to be used in the same way for hash code computation. I’ve checked and can reproduce it too (using .NET 4) … Read more
PostgreSQL UUID type performance
We had a table with about 30k rows that (for a specific unrelated architectural reason) had UUIDs stored in a text field and indexed. I noticed that the query perf was slower than I’d have expected. I created a new UUID column, copied in the text uuid primary key and compared below. 2.652ms vs 0.029ms. … Read more
Is order of a Ruby hash literal guaranteed?
There are couple of locations where this could be specified, i.e. a couple of things that are considered “The Ruby Language Specification”: the ISO Ruby Language Specification the RubySpec project the YARV testsuite The Ruby Programming Language book by matz and David Flanagan The ISO spec doesn’t say anything about Hash ordering: it was written … Read more
Probability of collision when using a 32-bit hash
Duplicate of Expected collisions for perfect 32bit crc The answer referenced this article: http://arstechnica.com/civis/viewtopic.php?f=20&t=149670 Found the image below from: http://preshing.com/20110504/hash-collision-probabilities