Add Hash#values_at vs Array#map { Hash#[] } comparison - #174
Conversation
Sorry, something went wrong.
|
DO NOT MERGE YET. Just noticed that #values_at and #slice#values return different results when Hash members are missing 🤦♂️ Will update the code and the benchmark, and see if it's still worth merging. |
Sorry, something went wrong.
|
This is faster than slice on my machine and returns the same as values_at: KEYS.map{ |key| HASH[key] } |
Sorry, something went wrong.
|
@Arcovion, cool! Will add it to the benchmark, too. Thanks! |
Sorry, something went wrong.
|
Added more ways of slicing Hash values, and organized them into three separate cases:
Thoughts? |
Sorry, something went wrong.
|
@kewlar I see the value in adding code/hash/values_at-vs-map.rb because it is quite straightforward and natural. But I don't see the value in adding the other benchmarks. The other examples are doing too many things and it is hard to tell which part makes one slower than the other. I'm happy to add code/hash/values_at-vs-map.rb if you submit just that in this PR or another PR. |
Sorry, something went wrong.
|
@etagwerker, thanks for the feedback! You're right, the other benchmarks are really just edge cases, and don't contribute much. And Hash#values_at is the best performing in them anyway. I've removed the redundant benchmarks. How does it look now? |
Sorry, something went wrong.
| d: 'qux' | ||
| }.freeze | ||
|
|
||
| # Some of the keys may not exist in the hash; we want to keep the default values. |
There was a problem hiding this comment.
For existing keys, the benchmark does not change much.
# frozen_string_literal: true
require 'benchmark/ips'
HASH = {
a: 'foo',
b: 'bar',
c: 'baz',
d: 'qux'
}.freeze
# the keys exist in the hash
KEYS = %i[a b c d].freeze
def fastest
HASH.values_at(*KEYS)
end
def slow
HASH.fetch_values(*KEYS)
end
def slowest
KEYS.map { |key| HASH[key] }
end
Benchmark.ips do |x|
x.report('Hash#values_at ') { fastest }
x.report('Hash#fetch_values ') { slow }
x.report('Array#map { Hash#[] }') { slowest }
x.compare!
endydakuka@yauhenid:~/ruby-docker-app$ docker run ruby-app
Warming up --------------------------------------
Hash#values_at
405.669k i/100ms
Hash#fetch_values
354.263k i/100ms
Array#map { Hash#[] }
221.960k i/100ms
Calculating -------------------------------------
Hash#values_at
4.191M (± 4.7%) i/s - 21.095M in 5.045130s
Hash#fetch_values
3.895M (± 6.8%) i/s - 19.484M in 5.031663s
Array#map { Hash#[] }
2.429M (± 6.1%) i/s - 12.208M in 5.048470s
Comparison:
Hash#values_at : 4190993.6 i/s
Hash#fetch_values : 3894866.5 i/s - same-ish: difference falls within error
Array#map { Hash#[] }: 2429428.6 i/s - 1.73x slower
Sorry, something went wrong.
No description provided.