In Erik Michaels-Ober's great talk, 'Writing Fast Ruby': Video @ Baruco 2014, Slide, he presented us with many idioms that lead to faster running Ruby code. He inspired me to document these to let more people know. I try to link to real commits so people can see that this can really have benefits in the real world. This does not mean you can always blindly replace one with another. It depends on the context (e.g. gsub versus tr). Friendly reminder: Use with caution!
Each idiom has a corresponding code example that resides in code.
All results listed in README.md are running with Ruby 2.2.0p0 on OS X 10.10.1. Machine information: MacBook Pro (Retina, 15-inch, Mid 2014), 2.5 GHz Intel Core i7, 16 GB 1600 MHz DDR3. Your results may vary, but you get the idea. : )
You can checkout the travis build for these benchmark results ran against different Ruby implementations.
Let's write faster code, together! <3
Checkout the fasterer project - it's a static analysis that checks speed idioms written in this repo.
Use benchmark-ips (2.0+).
require "benchmark/ips" def fast end def slow end Benchmark.ips do |x| x.report("fast code description") { fast } x.report("slow code description") { slow } x.compare! endParallel Assignment vs Sequential Assignment code
$ ruby -v code/general/assignment.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- Parallel Assignment 149.201k i/100ms Sequential Assignment 142.545k i/100ms ------------------------------------------------- Parallel Assignment 7.687M (± 6.9%) i/s - 38.345M Sequential Assignment 6.320M (± 8.5%) i/s - 31.360M Comparison: Parallel Assignment: 7686954.1 i/s Sequential Assignment: 6320425.6 i/s - 1.22x slower begin...rescue vs respond_to? for Control Flow code
$ ruby -v code/general/begin-rescue-vs-respond-to.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- begin...rescue 29.452k i/100ms respond_to? 106.528k i/100ms ------------------------------------------------- begin...rescue 371.591k (± 5.4%) i/s - 1.855M respond_to? 3.277M (± 7.5%) i/s - 16.299M Comparison: respond_to?: 3276972.3 i/s begin...rescue: 371591.0 i/s - 8.82x slower define_method vs module_eval for Defining Methods code
$ ruby -v code/general/define_method-vs-module-eval.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- module_eval with string 125.000 i/100ms define_method 138.000 i/100ms ------------------------------------------------- module_eval with string 1.130k (±20.3%) i/s - 5.500k define_method 1.346k (±25.9%) i/s - 6.348k Comparison: define_method: 1345.6 i/s module_eval with string: 1129.7 i/s - 1.19x slower raise vs E2MM#Raise for raising (and defining) exeptions code
Ruby's Exception2MessageMapper module allows one to define and raise exceptions with predefined messages.
$ ruby -v code/general/raise-vs-e2mmap.rb ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin14] Calculating ------------------------------------- Ruby exception: E2MM#Raise 2.865k i/100ms Ruby exception: Kernel#raise 42.215k i/100ms ------------------------------------------------- Ruby exception: E2MM#Raise 27.270k (± 8.8%) i/s - 137.520k Ruby exception: Kernel#raise 617.446k (± 7.9%) i/s - 3.082M Comparison: Ruby exception: Kernel#raise: 617446.2 i/s Ruby exception: E2MM#Raise: 27269.8 i/s - 22.64x slower Calculating ------------------------------------- Custom exception: E2MM#Raise 2.807k i/100ms Custom exception: Kernel#raise 45.313k i/100ms ------------------------------------------------- Custom exception: E2MM#Raise 29.005k (± 7.2%) i/s - 145.964k Custom exception: Kernel#raise 589.149k (± 7.8%) i/s - 2.945M Comparison: Custom exception: Kernel#raise: 589148.7 i/s Custom exception: E2MM#Raise: 29004.8 i/s - 20.31x slower loop vs while true code
$ ruby -v code/general/loop-vs-while-true.rb ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-linux] Calculating ------------------------------------- While Loop 1.000 i/100ms Kernel loop 1.000 i/100ms ------------------------------------------------- While Loop 0.536 (± 0.0%) i/s - 3.000 in 5.593042s Kernel loop 0.223 (± 0.0%) i/s - 2.000 in 8.982355s Comparison: While Loop: 0.5 i/s Kernel loop: 0.2 i/s - 2.41x slower call vs send vs method_missing code
$ ruby -v code/method/call-vs-send-vs-method_missing.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- call 115.094k i/100ms send 105.258k i/100ms method_missing 100.762k i/100ms ------------------------------------------------- call 3.811M (± 5.9%) i/s - 18.991M send 3.244M (± 7.2%) i/s - 16.210M method_missing 2.729M (± 9.8%) i/s - 13.401M Comparison: call: 3811183.4 i/s send: 3244239.1 i/s - 1.17x slower method_missing: 2728893.0 i/s - 1.40x slower Normal way to apply method vs &method(...) code
$ ruby -v code/general/block-apply-method.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- normal 85.749k i/100ms &method 35.529k i/100ms ------------------------------------------------- normal 1.867M (± 7.6%) i/s - 9.347M &method 467.095k (± 6.4%) i/s - 2.345M Comparison: normal: 1866669.5 i/s &method: 467095.4 i/s - 4.00x slower Function with single Array argument vs splat arguments code
$ ruby -v code/general/array-argument-vs-splat-arguments.rb ruby 2.1.7p400 (2015-08-18 revision 51632) [x86_64-linux-gnu] Calculating ------------------------------------- Function with single Array argument 157.231k i/100ms Function with splat arguments 4.983k i/100ms ------------------------------------------------- Function with single Array argument 5.581M (± 2.0%) i/s - 27.987M Function with splat arguments 54.428k (± 3.3%) i/s - 274.065k Comparison: Function with single Array argument: 5580972.6 i/s Function with splat arguments: 54427.7 i/s - 102.54x slower Ruby's [Exception2MessageMapper module](http://ruby-doc.org/stdlib-2.2.0/libdoc/e2mmap/rdoc/index.html) allows one to define and raise exceptions with predefined messages. Hash vs OpenStruct on access assuming you already have a Hash or an OpenStruct code
$ ruby -v code/general/hash-vs-openstruct-on-access.rb ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin14] Calculating ------------------------------------- Hash 128.344k i/100ms OpenStruct 110.723k i/100ms ------------------------------------------------- Hash 5.279M (± 7.0%) i/s - 26.311M OpenStruct 3.048M (± 7.0%) i/s - 15.169M Comparison: Hash: 5278844.0 i/s OpenStruct: 3048139.8 i/s - 1.73x slower Hash vs OpenStruct (creation) code
$ ruby -v code/general/hash-vs-openstruct.rb ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin14] Calculating ------------------------------------- Hash 75.510k i/100ms OpenStruct 9.126k i/100ms ------------------------------------------------- Hash 1.604M (±11.0%) i/s - 7.929M OpenStruct 96.855k (± 9.9%) i/s - 483.678k Comparison: Hash: 1604259.1 i/s OpenStruct: 96855.3 i/s - 16.56x slower Array#bsearch vs Array#find code
WARNING: bsearch ONLY works on sorted array. More details please see #29.
$ ruby -v code/array/bsearch-vs-find.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- find 1.000 i/100ms bsearch 42.216k i/100ms ------------------------------------------------- find 0.184 (± 0.0%) i/s - 1.000 in 5.434758s bsearch 577.301k (± 6.6%) i/s - 2.913M Comparison: bsearch: 577300.7 i/s find: 0.2 i/s - 3137489.63x slower Array#length vs Array#size vs Array#count code
Use #length when you only want to know how many elements in the array, #count could also archieve this. However #count should be use for counting specific elements in array. Note #size is an alias of #length.
$ ruby -v code/array/length-vs-size-vs-count.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- Array#length 172.998k i/100ms Array#size 168.130k i/100ms Array#count 164.911k i/100ms ------------------------------------------------- Array#length 11.394M (± 6.1%) i/s - 56.743M Array#size 11.303M (± 6.5%) i/s - 56.324M Array#count 9.195M (± 8.6%) i/s - 45.680M Comparison: Array#length: 11394036.7 i/s Array#size: 11302701.1 i/s - 1.01x slower Array#count: 9194976.2 i/s - 1.24x slower Array#shuffle.first vs Array#sample code
Array#shuffleallocates an extra array.
Array#sampleindexes into the array without allocating an extra array.
This is the reason why Array#sample exists.
—— @sferik rails/rails#17245
$ ruby -v code/array/shuffle-first-vs-sample.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Array#shuffle.first 25.406k i/100ms Array#sample 125.101k i/100ms ------------------------------------------------- Array#shuffle.first 304.341k (± 4.3%) i/s - 1.524M Array#sample 5.727M (± 8.6%) i/s - 28.523M Comparison: Array#sample: 5727032.0 i/s Array#shuffle.first: 304341.1 i/s - 18.82x slower Array#[](0) vs Array#first code
$ ruby -v code/array/array-first-vs-index.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Array#[0] 152.751k i/100ms Array#first 148.088k i/100ms ------------------------------------------------- Array#[0] 8.614M (± 7.0%) i/s - 42.923M Array#first 7.465M (±10.7%) i/s - 36.874M Comparison: Array#[0]: 8613583.7 i/s Array#first: 7464526.6 i/s - 1.15x slower Array#[](-1) vs Array#last code
$ ruby -v code/array/array-last-vs-index.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Array#[-1] 151.940k i/100ms Array#last 153.371k i/100ms ------------------------------------------------- Array#[-1] 8.582M (± 4.6%) i/s - 42.847M Array#last 7.639M (± 5.7%) i/s - 38.189M Comparison: Array#[-1]: 8582074.3 i/s Array#last: 7639254.5 i/s - 1.12x slower Array#insert vs Array#unshift code
$ ruby -v code/array/insert-vs-unshift.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin10.0] Calculating ------------------------------------- Array#unshift 4.000 i/100ms Array#insert 1.000 i/100ms ------------------------------------------------- Array#unshift 44.947 (± 6.7%) i/s - 224.000 Array#insert 0.171 (± 0.0%) i/s - 1.000 in 5.841595s Comparison: Array#unshift: 44.9 i/s Array#insert: 0.2 i/s - 262.56x slower Enumerable#each + push vs Enumerable#map code
$ ruby -v code/enumerable/each-push-vs-map.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Array#each + push 9.025k i/100ms Array#map 13.947k i/100ms ------------------------------------------------- Array#each + push 99.634k (± 3.2%) i/s - 505.400k Array#map 158.091k (± 4.2%) i/s - 794.979k Comparison: Array#map: 158090.9 i/s Array#each + push: 99634.2 i/s - 1.59x slower Enumerable#each vs for loop code
$ ruby -v code/enumerable/each-vs-for-loop.rb ruby 2.2.0preview1 (2014-09-17 trunk 47616) [x86_64-darwin14] Calculating ------------------------------------- For loop 17.111k i/100ms #each 18.464k i/100ms ------------------------------------------------- For loop 198.517k (± 5.3%) i/s - 992.438k #each 208.157k (± 5.0%) i/s - 1.052M Comparison: #each: 208157.4 i/s For loop: 198517.3 i/s - 1.05x slower Enumerable#each_with_index vs while loop code
$ ruby -v code/enumerable/each_with_index-vs-while-loop.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- While Loop 22.553k i/100ms each_with_index 11.963k i/100ms ------------------------------------------------- While Loop 240.752k (± 7.1%) i/s - 1.218M each_with_index 126.753k (± 5.9%) i/s - 634.039k Comparison: While Loop: 240752.1 i/s each_with_index: 126753.4 i/s - 1.90x slower Enumerable#map...Array#flatten vs Enumerable#flat_map code
-- @sferik rails/rails@3413b88, Replace map.flatten with flat_map, Replace map.flatten(1) with flat_map
$ ruby -v code/enumerable/map-flatten-vs-flat_map.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Array#map.flatten(1) 3.315k i/100ms Array#map.flatten 3.283k i/100ms Array#flat_map 5.350k i/100ms ------------------------------------------------- Array#map.flatten(1) 33.801k (± 4.3%) i/s - 169.065k Array#map.flatten 34.530k (± 6.0%) i/s - 173.999k Array#flat_map 55.980k (± 5.0%) i/s - 283.550k Comparison: Array#flat_map: 55979.6 i/s Array#map.flatten: 34529.6 i/s - 1.62x slower Array#map.flatten(1): 33800.6 i/s - 1.66x slower Enumerable#reverse.each vs Enumerable#reverse_each code
Enumerable#reverseallocates an extra array.
Enumerable#reverse_eachyields each value without allocating an extra array.
This is the reason whyEnumerable#reverse_eachexists.
-- @sferik rails/rails#17244
$ ruby -v code/enumerable/reverse-each-vs-reverse_each.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Array#reverse.each 16.746k i/100ms Array#reverse_each 18.590k i/100ms ------------------------------------------------- Array#reverse.each 190.729k (± 4.8%) i/s - 954.522k Array#reverse_each 216.060k (± 4.3%) i/s - 1.078M Comparison: Array#reverse_each: 216060.5 i/s Array#reverse.each: 190729.1 i/s - 1.13x slower Enumerable#detect vs Enumerable#select.first code
$ ruby -v code/enumerable/select-first-vs-detect.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Enumerable#select.first 8.515k i/100ms Enumerable#detect 33.885k i/100ms ------------------------------------------------- Enumerable#select.first 89.757k (± 5.0%) i/s - 1.797M Enumerable#detect 434.304k (± 5.2%) i/s - 8.675M Comparison: Enumerable#detect: 434304.2 i/s Enumerable#select.first: 89757.4 i/s - 4.84x slower Enumerable#select.last vs Enumerable#reverse.detect code
$ ruby -v code/enumerable/select-last-vs-reverse-detect.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Enumerable#reverse.detect 62.636k i/100ms Enumerable#select.last 11.687k i/100ms ------------------------------------------------- Enumerable#reverse.detect 1.263M (± 8.2%) i/s - 6.326M Enumerable#select.last 119.387k (± 5.7%) i/s - 596.037k Comparison: Enumerable#reverse.detect: 1263100.2 i/s Enumerable#select.last: 119386.8 i/s - 10.58x slower Enumerable#sort vs Enumerable#sort_by code
$ ruby -v code/enumerable/sort-vs-sort_by.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- Enumerable#sort_by (Symbol#to_proc) 2.680k i/100ms Enumerable#sort_by 2.462k i/100ms Enumerable#sort 1.320k i/100ms ------------------------------------------------- Enumerable#sort_by (Symbol#to_proc) 25.916k (± 4.4%) i/s - 131.320k Enumerable#sort_by 24.650k (± 5.1%) i/s - 125.562k Enumerable#sort 14.018k (± 5.6%) i/s - 69.960k Comparison: Enumerable#sort_by (Symbol#to_proc): 25916.1 i/s Enumerable#sort_by: 24650.2 i/s - 1.05x slower Enumerable#sort: 14018.3 i/s - 1.85x slower Hash#[] vs Hash#fetch code
If you use Ruby 2.2, Symbol could be more performant than String as Hash keys. Read more regarding this: Symbol GC in Ruby 2.2 and Unraveling String Key Performance in Ruby 2.2.
$ ruby -v code/hash/bracket-vs-fetch.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- Hash#[], symbol 143.850k i/100ms Hash#fetch, symbol 137.425k i/100ms Hash#[], string 143.083k i/100ms Hash#fetch, string 120.417k i/100ms ------------------------------------------------- Hash#[], symbol 7.531M (± 6.6%) i/s - 37.545M Hash#fetch, symbol 6.644M (± 8.2%) i/s - 32.982M Hash#[], string 6.657M (± 7.7%) i/s - 33.195M Hash#fetch, string 3.981M (± 8.7%) i/s - 19.748M Comparison: Hash#[], symbol: 7531355.8 i/s Hash#[], string: 6656818.8 i/s - 1.13x slower Hash#fetch, symbol: 6643665.5 i/s - 1.13x slower Hash#fetch, string: 3981166.5 i/s - 1.89x slower Hash[] vs Hash#dup code
Source: http://tenderlovemaking.com/2015/02/11/weird-stuff-with-hashes.html
Does this mean that you should switch to Hash[]? Only if your benchmarks can prove that it’s a bottleneck. Please please please don’t change all of your code because this shows it’s faster. Make sure to measure your app performance first.
$ ruby -v code/hash/bracket-vs-dup.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Hash[] 29.403k i/100ms Hash#dup 16.195k i/100ms ------------------------------------------------- Hash[] 343.987k (± 8.7%) i/s - 1.735M Hash#dup 163.516k (±10.2%) i/s - 825.945k Comparison: Hash[]: 343986.5 i/s Hash#dup: 163516.3 i/s - 2.10x slower Hash#fetch with argument vs Hash#fetch + block code
Note that the speedup in the block version comes from avoiding repeated
construction of the argument. If the argument is a constant, number symbol or
something of that sort the argument version is actually slightly faster
See also #39 (comment)
$ ruby -v code/hash/fetch-vs-fetch-with-block.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin13] Calculating ------------------------------------- Hash#fetch + const 129.868k i/100ms Hash#fetch + block 125.254k i/100ms Hash#fetch + arg 121.155k i/100ms ------------------------------------------------- Hash#fetch + const 7.031M (± 7.0%) i/s - 34.934M Hash#fetch + block 6.815M (± 4.2%) i/s - 34.069M Hash#fetch + arg 4.753M (± 5.6%) i/s - 23.746M Comparison: Hash#fetch + const: 7030600.4 i/s Hash#fetch + block: 6814826.7 i/s - 1.03x slower Hash#fetch + arg: 4752567.2 i/s - 1.48x slower Hash#each_key instead of Hash#keys.each code
Hash#keys.eachallocates an array of keys;
Hash#each_keyiterates through the keys without allocating a new array.
This is the reason whyHash#each_keyexists.
—— @sferik rails/rails#17099
$ ruby -v code/hash/keys-each-vs-each_key.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Hash#keys.each 56.690k i/100ms Hash#each_key 59.658k i/100ms ------------------------------------------------- Hash#keys.each 869.262k (± 5.0%) i/s - 4.365M Hash#each_key 1.049M (± 6.0%) i/s - 5.250M Comparison: Hash#each_key: 1049161.6 i/s Hash#keys.each: 869262.3 i/s - 1.21x slower Hash#merge! vs Hash#[]= code
$ ruby -v code/hash/merge-bang-vs-\[\]=.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Hash#merge! 1.023k i/100ms Hash#[]= 2.844k i/100ms ------------------------------------------------- Hash#merge! 10.653k (± 4.9%) i/s - 53.196k Hash#[]= 28.287k (±12.4%) i/s - 142.200k Comparison: Hash#[]=: 28287.1 i/s Hash#merge!: 10653.3 i/s - 2.66x slower Hash#merge vs Hash#merge! code
$ ruby -v code/hash/merge-vs-merge-bang.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Hash#merge 39.000 i/100ms Hash#merge! 1.008k i/100ms ------------------------------------------------- Hash#merge 409.610 (± 7.6%) i/s - 2.067k Hash#merge! 9.830k (± 5.8%) i/s - 49.392k Comparison: Hash#merge!: 9830.3 i/s Hash#merge: 409.6 i/s - 24.00x slower {}#merge!(Hash) vs Hash#merge({}) vs Hash#dup#merge!({}) code
When we don't want to modify the original hash, and we want duplicates to be created
See #42 for more details.
$ ruby -v code/hash/merge-bang-vs-merge-vs-dup-merge-bang.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- {}#merge!(Hash) 1.082k i/100ms Hash#merge({}) 422.000 i/100ms Hash#dup#merge!({}) 419.000 i/100ms ------------------------------------------------- {}#merge!(Hash) 11.161k (± 5.1%) i/s - 56.264k Hash#merge({}) 4.449k (± 3.8%) i/s - 22.366k Hash#dup#merge!({}) 4.340k (± 6.2%) i/s - 21.788k Comparison: {}#merge!(Hash): 11161.3 i/s Hash#merge({}): 4449.4 i/s - 2.51x slower Hash#dup#merge!({}): 4340.3 i/s - 2.57x slower Hash#sort_by vs Hash#sort code
To sort hash by key.
$ ruby -v code/hash/hash-key-sort_by-vs-sort.rb ruby 2.2.1p85 (2015-02-26 revision 49769) [x86_64-darwin14] Calculating ------------------------------------- sort_by + to_h 11.468k i/100ms sort + to_h 8.107k i/100ms ------------------------------------------------- sort_by + to_h 122.176k (± 6.0%) i/s - 619.272k sort + to_h 81.973k (± 4.7%) i/s - 413.457k Comparison: sort_by + to_h: 122176.2 i/s sort + to_h: 81972.8 i/s - 1.49x slower Block vs Symbol#to_proc code
Symbol#to_procis considerably more concise than using block syntax.
...In some cases, it reduces the number of lines of code.
—— @sferik rails/rails#16833
$ ruby -v code/proc-and-block/block-vs-to_proc.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- Block 4.632k i/100ms Symbol#to_proc 5.225k i/100ms ------------------------------------------------- Block 47.914k (± 6.3%) i/s - 240.864k Symbol#to_proc 54.791k (± 4.1%) i/s - 276.925k Comparison: Symbol#to_proc: 54791.1 i/s Block: 47914.3 i/s - 1.14x slower Proc#call and block arguments vs yieldcode
In MRI Ruby, block arguments are converted to Procs, which incurs a heap allocation.
$ ruby -v code/proc-and-block/proc-call-vs-yield.rb ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin15] Calculating ------------------------------------- block.call 41.978k i/100ms block + yield 42.674k i/100ms block argument 41.722k i/100ms yield 62.681k i/100ms ------------------------------------------------- block.call 842.581k (±12.5%) i/s - 4.114M block + yield 941.468k (±11.7%) i/s - 4.651M block argument 1.043M (± 7.1%) i/s - 5.215M yield 3.828M (±11.3%) i/s - 18.930M Comparison: yield: 3828436.1 i/s block argument: 1042509.6 i/s - 3.67x slower block + yield: 941467.7 i/s - 4.07x slower block.call: 842581.2 i/s - 4.54x slower String#casecmp vs String#downcase + == code
$ ruby -v code/string/casecmp-vs-downcase-\=\=.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- String#downcase + == 101.900k i/100ms String#casecmp 109.828k i/100ms ------------------------------------------------- String#downcase + == 2.915M (± 5.4%) i/s - 14.572M String#casecmp 3.708M (± 6.1%) i/s - 18.561M Comparison: String#casecmp: 3708258.7 i/s String#downcase + ==: 2914767.7 i/s - 1.27x slower String Concatenation code
$ ruby -v code/string/concatenation.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- String#+ 96.314k i/100ms String#concat 99.850k i/100ms String#append 100.728k i/100ms "foo" "bar" 121.936k i/100ms ------------------------------------------------- String#+ 2.731M (± 4.6%) i/s - 13.677M String#concat 2.847M (± 5.2%) i/s - 14.279M String#append 2.972M (± 6.1%) i/s - 14.807M "foo" "bar" 4.951M (± 6.2%) i/s - 24.753M Comparison: "foo" "bar": 4950955.3 i/s String#append: 2972048.5 i/s - 1.67x slower String#concat: 2846666.4 i/s - 1.74x slower String#+: 2730980.7 i/s - 1.81x slower String#match vs String#start_with?/String#end_with? code (start) code (end)
⚠️
Sometimes you cant replace regexp withstart_with?,
for example:"a\nb" =~ /^b/ #=> 2but"a\nb" =~ /\Ab/ #=> nil.
⚠️
You can combinestart_with?andend_with?to replaceerror.path =~ /^#{path}(\.rb)?$/to this
error.path.start_with?(path) && error.path.end_with?('.rb', '')
—— @igas rails/rails#17316
$ ruby -v code/string/start-string-checking-match-vs-start_with.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- String#=~ 56.672k i/100ms String#start_with? 118.308k i/100ms ------------------------------------------------- String#=~ 919.574k (± 6.4%) i/s - 4.590M String#start_with? 4.177M (± 6.4%) i/s - 20.822M Comparison: String#start_with?: 4177162.6 i/s String#=~: 919574.2 i/s - 4.54x slower $ ruby -v code/string/end-string-checking-match-vs-end_with.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- String#=~ 53.194k i/100ms String#end_with? 105.871k i/100ms ------------------------------------------------- String#=~ 891.124k (± 7.2%) i/s - 4.468M String#end_with? 2.942M (± 7.6%) i/s - 14.610M Comparison: String#end_with?: 2942017.4 i/s String#=~: 891124.1 i/s - 3.30x slower Regexp#=== vs String#match vs String#=~ code
⚠️
Sometimes you can't replacematchwith=~,
This is only useful for cases where you are checking
for a match and not using the resultant match object.
⚠️
Regexp#===is also faster thanString#matchbut you need to switch the order of arguments.
$ ruby -v code/string/===-vs-=~-vs-match.rb.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- String#=~ 98.184k i/100ms Regexp#=== 92.382k i/100ms String#match 83.601k i/100ms ------------------------------------------------- String#=~ 2.442M (± 7.6%) i/s - 12.175M Regexp#=== 2.259M (± 7.9%) i/s - 11.271M String#match 1.840M (± 7.3%) i/s - 9.196M Comparison: String#=~: 2442335.1 i/s Regexp#===: 2259277.3 i/s - 1.08x slower String#match: 1839815.4 i/s - 1.33x slower See #59 and #62 for discussions.
String#gsub vs String#sub code
$ ruby -v code/string/gsub-vs-sub.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- String#gsub 35.724k i/100ms String#sub 42.426k i/100ms ------------------------------------------------- String#gsub 486.614k (± 5.4%) i/s - 2.429M String#sub 611.259k (± 4.6%) i/s - 3.055M Comparison: String#sub: 611259.4 i/s String#gsub: 486613.5 i/s - 1.26x slower String#gsub vs String#tr code
$ ruby -v code/string/gsub-vs-tr.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- String#gsub 38.268k i/100ms String#tr 83.210k i/100ms ------------------------------------------------- String#gsub 516.604k (± 4.4%) i/s - 2.602M String#tr 1.862M (± 4.0%) i/s - 9.320M Comparison: String#tr: 1861860.4 i/s String#gsub: 516604.2 i/s - 3.60x slower String#sub! vs String#gsub! vs String#[]= code
Note that String#[] will throw an IndexError when given string or regexp not matched.
$ ruby -v code/string/sub\!-vs-gsub\!-vs-\[\]\=.rb ruby 2.2.2p95 (2015-04-13 revision 50295) [x86_64-darwin14] Calculating ------------------------------------- String#['string']= 74.512k i/100ms String#sub!'string' 52.801k i/100ms String#gsub!'string' 34.480k i/100ms String#[/regexp/]= 55.325k i/100ms String#sub!/regexp/ 45.770k i/100ms String#gsub!/regexp/ 27.665k i/100ms ------------------------------------------------- String#['string']= 1.215M (± 6.2%) i/s - 6.110M String#sub!'string' 752.731k (± 6.2%) i/s - 3.749M String#gsub!'string' 481.183k (± 4.4%) i/s - 2.414M String#[/regexp/]= 840.615k (± 5.3%) i/s - 4.205M String#sub!/regexp/ 663.075k (± 7.8%) i/s - 3.295M String#gsub!/regexp/ 342.004k (± 7.5%) i/s - 1.715M Comparison: String#['string']=: 1214845.5 i/s String#[/regexp/]=: 840615.2 i/s - 1.45x slower String#sub!'string': 752731.4 i/s - 1.61x slower String#sub!/regexp/: 663075.3 i/s - 1.83x slower String#gsub!'string': 481183.5 i/s - 2.52x slower String#gsub!/regexp/: 342003.8 i/s - 3.55x slower String#sub vs String#chomp code
Note that this can only be used for removing characters from the end of a string.
$ ruby -v code/string/sub-vs-chomp.rb ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-darwin13] Calculating ------------------------------------- String#sub/regexp/ 42.816k i/100ms String#chomp'string' 94.851k i/100ms ------------------------------------------------- String#sub/regexp/ 660.509k (± 8.0%) i/s - 3.297M String#chomp'string' 2.803M (± 8.0%) i/s - 13.943M Comparison: String#chomp'string': 2803443.5 i/s String#sub/regexp/: 660508.7 i/s - 4.24x slower attr_accessor vs getter and setter code
https://www.omniref.com/ruby/2.2.0/files/method.h?#annotation=4081781&line=47
$ ruby -v code/general/attr-accessor-vs-getter-and-setter.rb ruby 2.2.0p0 (2014-12-25 revision 49005) [x86_64-darwin14] Calculating ------------------------------------- getter_and_setter 61.240k i/100ms attr_accessor 66.535k i/100ms ------------------------------------------------- getter_and_setter 1.660M (± 9.7%) i/s - 8.267M attr_accessor 1.865M (± 9.2%) i/s - 9.248M Comparison: attr_accessor: 1865408.4 i/s getter_and_setter: 1660021.9 i/s - 1.12x slower cover? vs include? code
cover? only check if it is within the start and end, include? needs to traverse the whole range.
$ ruby -v code/range/cover-vs-include.rb ruby 2.2.3p173 (2015-08-18 revision 51636) [x86_64-linux] Calculating ------------------------------------- range#cover? 85.467k i/100ms range#include? 7.720k i/100ms range#member? 7.783k i/100ms plain compare 102.189k i/100ms ------------------------------------------------- range#cover? 1.816M (± 5.6%) i/s - 9.060M range#include? 83.344k (± 5.0%) i/s - 416.880k range#member? 82.654k (± 5.0%) i/s - 412.499k plain compare 2.581M (± 6.2%) i/s - 12.876M Comparison: plain compare: 2581211.8 i/s range#cover?: 1816038.5 i/s - 1.42x slower range#include?: 83343.9 i/s - 30.97x slower range#member?: 82654.1 i/s - 31.23x slower Please! Edit this README.md then Submit a Awesome Pull Request!
Code example is wrong? 😢 Got better example? 😍 Excellent!
Please open an issue or Open a Pull Request to fix it.
Thank you in advance! 😉 🍺
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