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Avoid allocating the second array by using `Array#reject!` instead of
`Enumerable#partition` in `Array#extract!`.
There are benchmarks in order to ensure that the changes speed up the method:
```
begin
require "bundler/inline"
rescue LoadError => e
$stderr.puts "Bundler version 1.10 or later is required. Please update
your Bundler"
raise e
end
class Array
def extract_v1!(&block)
unless block_given?
to_enum(:extract!) { size }
else
extracted_elements, other_elements = partition(&block)
replace(other_elements)
extracted_elements
end
end
def extract_v2!
return to_enum(:extract!) { size } unless block_given?
extracted_elements = []
reject! do |element|
extracted_elements << element if yield(element)
end
extracted_elements
end
end
gemfile(true) do
source "https://rubygems.org"
gem "benchmark-ips"
end
arrays_for_partition = Array.new(1000) { (0..10000).to_a }
arrays_for_extract_v1 = Array.new(1000) { (0..10000).to_a }
arrays_for_extract_v2 = Array.new(1000) { (0..10000).to_a }
Benchmark.ips do |x|
x.report("Array#partition") do
arrays_for_partition.each do |numbers|
odd_numbers, numbers = numbers.partition { |number| number.odd? }
numbers
end
end
x.report("Array#extract_v1!") do
arrays_for_extract_v1.each do |numbers|
odd_numbers = numbers.extract_v1! { |number| number.odd? }
numbers
end
end
x.report("Array#extract_v2!") do
arrays_for_extract_v2.each do |numbers|
odd_numbers = numbers.extract_v2! { |number| number.odd? }
numbers
end
end
x.compare!
end
```
The result of the benchmarks:
```
ruby -v
ruby 2.5.1p57 (2018-03-29 revision 63029) [x86_64-linux]
```
```
Fetching gem metadata from https://rubygems.org/.
Resolving dependencies...
Using benchmark-ips 2.7.2
Using bundler 1.16.1
Warming up --------------------------------------
Array#partition 1.000 i/100ms
Array#extract_v1! 1.000 i/100ms
Array#extract_v2! 1.000 i/100ms
Calculating -------------------------------------
Array#partition 1.390 (± 0.0%) i/s - 7.000 in 5.044843s
Array#extract_v1! 2.781 (± 0.0%) i/s - 14.000 in 5.050589s
Array#extract_v2! 3.151 (± 0.0%) i/s - 16.000 in 5.080608s
Comparison:
Array#extract_v2!: 3.2 i/s
Array#extract_v1!: 2.8 i/s - 1.13x slower
Array#partition: 1.4 i/s - 2.27x slower
```
Avoid `unless`/`else` in favour of an early return.
The double-negative of that `else` can be confusing,
even though the code layout is nearly the same.
Also using of early return would improve `git diff`
if we needed to change this method.
|
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The method removes and returns the elements for which the block returns a true value.
If no block is given, an Enumerator is returned instead.
```
numbers = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
odd_numbers = numbers.extract! { |number| number.odd? } # => [1, 3, 5, 7, 9]
numbers # => [0, 2, 4, 6, 8]
```
|
