You can’t do what you’re trying to do: bash arrays are one-dimensional $ declare -A PERSONS $ declare -A PERSON $ PERSON[“FNAME”]=’John’ $ PERSON[“LNAME”]=’Andrew’ $ declare -p PERSON declare -A PERSON='([FNAME]=”John” [LNAME]=”Andrew” )’ $ PERSONS[1]=([FNAME]=”John” [LNAME]=”Andrew” ) bash: PERSONS[1]: cannot assign list to array member You can fake multidimensionality by composing a suitable array index … Read more
In Computing Science terminology, a map is an associative container mapping from a key to a value. In other words, you can do operations like “for key K remember value V” and later “for key K get the value”. A map can be implemented in many ways – for example, with a (optionally balanced) binary … Read more
foreach my $key (keys %$ad_grp_ref) { … } Perl::Critic and daxim recommend the style foreach my $key (keys %{ $ad_grp_ref }) { … } out of concerns for readability and maintenance (so that you don’t need to think hard about what to change when you need to use %{ $ad_grp_obj[3]->get_ref() } instead of %{ $ad_grp_ref … Read more
It depends on your use case. You can’t broadly claim “superiority”. (I mean, yes you can, in some cases, but to be strict about it, you can’t really). But there are areas where MD5 has been broken: For starters: MD5 is old, and common. There are tons of rainbow tables against it, and they’re easy … Read more
The problem being solved is that the previous hash algorithm in Lib/sets.py had horrendous performance on datasets that arise in a number of graph algorithms (where nodes are represented as frozensets): # Old-algorithm with bad performance def _compute_hash(self): result = 0 for elt in self: result ^= hash(elt) return result def __hash__(self): if self._hashcode is … Read more
My solution, one among the others 🙂 a = [“a”, “b”, “c”, “d”] h = Hash[a.map {|x| [x, 1]}]
The seed parameter is a means for you to randomize the hash function. You should provide the same seed value for all calls to the hashing function in the same application of the hashing function. However, each invocation of your application (assuming it is creating a new hash table) can use a different seed, e.g., … Read more
Using a power of two effectively masks out top bits of the hash code. Thus a poor-quality hash function might perform particularly badly in this scenario. Java’s HashMap mitigates this by mistrusting the object’s hashCode() implementation and applying a second level of hashing to its result: Applies a supplemental hash function to a given hashCode, … Read more
there are lot of such functionality in ruby’s digest module: http://ruby-doc.org/stdlib/libdoc/digest/rdoc/index.html simple example: require ‘digest/sha1’ Digest::SHA1.hexdigest(“some string”)