Saving People from Typos

4 B W J O H 1F P Q
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!ZVLJ 4PGUXBSF&OHJOFFSBU : 6 , * / * 4
) * + * . " ੢ ౢ ༔ و

!ZVLJ 4PGUXBSF&OHJOFFSBU $PNNJUFS : 6 , * / *
4 ) * + * . " ੢ ౢ ༔ و

!ZVLJ .BJOUBJOFSPGkaminari : 6 , * / * 4
) * + * . " ੢ ౢ ༔ و

!ZVLJ .BJOUBJOFSPGkaminari $SFBUPSPGdid_you_mean : 6 , * / *
4 ) * + * . " ੢ ౢ ༔ و

4 B W J O H 1F P Q
M F G S P N 5Z Q P T

"Yuki".starts_with?("Y")

"Yuki".starts_with?("Y") # => NoMethodError: undefined method # `starts_with?’ for “Yuki":String

"Yuki".start_with?("Y") # => true

8 ) : $ " / ` 5
3 6 # : % 0 5 ) & 4 " . &

3 6 # : * 4 % &
4 * ( / & % 5 0 . " , & 1 3 0 ( 3 " . . & 3 4 ) " 1 1 :

8 ) : $ " / ` 5
3 6 # : % 0 5 ) & 4 " . &

5 I F d i d _ y o
u _ m e a n H F N

"Yuki".start_with?("Y") # => true

require "did_you_mean" "Yuki".starts_with?("Y") # => NoMethodError: undefined method # `starts_with?’
for “Yuki":String "Yuki".start_with?("Y") # => true

require "did_you_mean" "Yuki".starts_with?("Y") # => NoMethodError: undefined method # `starts_with?’
for “Yuki":String # # Did you mean? start_with? # "Yuki".start_with?("Y") # => true

) 0 8 % 0 & 4 *
5 8 0 3 ,

w " T Q F M M D
I F D L F S w . P O L F Z Q B U D I F T

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4QFMMDIFDLFS *OQVU 0VUQVU XJUIOPJTF

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w %JDUJPOBSZ * / 4 * % & 5
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w %JDUJPOBSZ w $POUSPMNFDIBOJTN * / 4 * % &
5 ) & 4 1 & - - $ ) & $ , & 3

w %JDUJPOBSZ w $POUSPMNFDIBOJTN w 0QUJNJ[BUJPO * / 4 *
% & 5 ) & 4 1 & - - $ ) & $ , & 3

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0 1 5 * . * ; "5 * 0
/ w *NQSPWFTQFSGPSNBODFBOEPSBDDVSBDZ w 0QUJNJ[BUJPOUFDIOJRVFTNBZCFDPOUFYUTQFDJpD w (SBNNBSBOBMZTJT w 4UBUJTUJDBMNPEFM w 1SPOVODJBUJPOCBTFEDPSSFDUJPO

l 5 I F Z X F F S
F U S B W F M J O H U I S P V H I U I F O J H I U z

XFSF XIFSF l 5 I F Z X F
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X F F S F U S B W F M J O H U I S P V H I U I F O J H I U z

l 5 I F Z O P I
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u _ m e a n H F N w %JDUJPOBSZ w "TFUPGTZNCPMT w $POUSPMNFDIBOJTN w 6TFT-FWFOTIUFJOEJTUBODFUPDPSSFDUNJTUZQFEXPSET w 6TFT+BSP8JOLMFSEJTUBODFUPDPSSFDUNJTTQFMUXPSET w 0QUJNJ[BUJPO w $POUFYUCBTFEEJDUJPOBSZ

Symbol.all_symbols % J D U J P O B S
Z

NameError NoMethodError 6OJOJUJBMJ[FEDPOTUBOU ClassNameChecker VariableNameChecker PUIFSFSSPST MethodNameChecker O P T
I M I Z AT I O N

. J T U Z Q F $ P
S S F D U J P O . J T T Q F M M $ P S S F D U J P O C O N T R O L M E C H A N I S M

8IZ/FFET5ZQFTPG$POUSPM.FDIBOJTN .JTUZQFEXPSET w 5IFDPSSFDUTQFMMJOHJTDPSSFDUMZSFNFNCFSFE CVUPOFPSNPSF JODPSSFDUMFUUFSTBSFUZQFECZNJTUBLF w DPSSFDUFECZUIFdid_you_meanHFNVTJOH-FWFOTIUFJOEJTUBODF .JTTQFMUXPSET w
5IFDPSSFDUTQFMMJOHJTNJTSFNFNCFSFEPSOPUSFNFNCFSFEBUBMM w 5IFpSTUDIBSBDUFSJTBMXBZTDPSSFDU • Yannakoudakis, E.J. and Fawthrop, D., "The rules of spelling errors," Information Processing and Management, vol. 19, no. 2, pp. 87-99, 1983. w DPSSFDUFECZUIFdid_you_mean HFNVTJOH+BSP8JOLMFSEJTUBODF

. J T U Z Q F $ P
S S F D U J P O . J T T Q F M M $ P S S F D U J P O

- F W F O T I U F J
O % J T U B O D F

start_with starts_with - F W F O T I U
F J O % J T U B O D F

start_with starts_with - F W F O T I U
F J O % J T U B O D F 5IFEJTUBODFJT ✅JOTFSUJPO

first_name full_name - F W F O T I U
F J O % J T U B O D F

F J O % J T U B O D F ✅ ✅ ✅ TVCTUJUVUJPO

F J O % J T U B O D F ✅ ✅ ✅ ✅ 5IFEJTUBODFJT EFMFUJPO TVCTUJUVUJPO

.JTUZQF$PSSFDUJPO threshold = (input.length * 0.25).ceil dictionary.select do |word| Levenshtein.distance(word,
input) <= threshold end

. J T U Z Q F $ P
S S F D U J P O . J T T Q F M M $ P S S F D U J P O

+ B S P 8 J O L M
F S % J T U B O D F

+ B S P % J T U B
O D F 1 S F G J Y # P O V T

+ B S P % J T U B
O D F

+BSP%JTUBODF m : the number of matching characters t :
half the number of transpositions

first_name frist_name +BSP%JTUBODF

+BSP%JTUBODF first_name frist_name

+BSP%JTUBODF ??? first_name frist_name

.BUDIJOHXJOEPX l1 = length of string1 l2 = length of
string2

first_name frist_name +BSP%JTUBODF ⛔ Matching window = (10 / 2)
- 1 = 4

first_name frist_name +BSP%JTUBODF mJT10

first_name frist_name +BSP%JTUBODF ✅ ✅

first_name frist_name +BSP%JTUBODF ✅ ✅ tJT1 IBMGOVNCFSPGUSBOTQPTJUJPOT

+BSP%JTUBODF m : 10 (the number of matching letters) t
: 1 (half the number of transpositions)

m : 10 (the number of matching letters) t :
1 (half the number of transpositions) 5IFEJTUBODFJT0.9666… +BSP%JTUBODF

1SFpY#POVT

first_name frist_name 1SFpY#POVT

first_name frist_name ? ? ? ? 1SFpY#POVT

first_name frist_name 1SFpY#POVT

first_name frist_name ⛔ 1SFpY#POVT

1SFpY#POVT w = 0.1 (weight) mp = number of prefix
matches j = Jaro distance

5IFQSFpYCPOVTJT0.0033… 1SFpY#POVT w = 0.1 (weight) mp = number of
prefix matches j = Jaro distance

+BSP8JOLMFS%JTUBODF Jaro-Winkler distance = 0.9666… + 0.0033… = 0.9699…

.JTTQFMM$PSSFDUJPO w 1JDLTVQUIFDMPTFTUXPSEPOMZJG w /PNJTUZQFDPSSFDUJPOTBSFGPVOE w 5IF-FWFOTIUFJOEJTUBODFJTMPXFSUIBOUIFMFOHUIPG UIFTIPSUFSTUSJOH d =
Levenshtein distance between 2 strings l1 = length of string1 l2 = length of string2

I U U Q H J U
J P W 3 E : 8 5 I F E J E @ Z P V @ N F B O ` T 4 Q F M M $ I F D L F S

" T Q F M M D I
F D L F S . P O L F Z Q B U D I F T ✅

w /BNF&SSPS w /P.FUIPE&SSPS 4QFMMDIFDLFS

w /BNF&SSPS w /P.FUIPE&SSPS 4QFMMDIFDLFS 6TFSJOQVU %JDUJPOBSZ

w /BNF&SSPS w /P.FUIPE&SSPS 4QFMMDIFDLFS 6TFSJOQVU %JDUJPOBSZ “Did you mean?
…”

07 & 3 3 * % * / (
5 ) & & 3 3 0 3 . & 4 4 "( & module DidYouMean module NameErrorExtension prepend_features NameError def to_s super + Formatter.new(corrections).to_s rescue super end def corrections SPELL_CHECKERS[self.class.to_s].new(self).corrections end end end

module DidYouMean module NameErrorExtension prepend_features NameError def to_s super +
Formatter.new(corrections).to_s rescue super end def corrections SPELL_CHECKERS[self.class.to_s].new(self).corrections end end end 07 & 3 3 * % * / ( 5 ) & & 3 3 0 3 . & 4 4 "( &

* / 4 * % & 5 ) &
* / * 5 * " - * ; & 3 module DidYouMean class ANameChecker include SpellCheckable def initialize(exception) # pull out the user input and generate # a dictionary using the exception object. end end end

NameError#name

NameError#name begin doesnt_exist rescue NameError => error error.name # =>
:doesnt_exist end begin DoesntExist rescue NameError => error error.name # => :DoesntExist end begin @@doesnt_exist rescue NameError => error error.name # => :@@doesnt_exist end

NameError#name begin doesnt_exist("argument") rescue NoMethodError => error error.name # =>
:doesnt_exist end begin self.doesnt_exist rescue NoMethodError => error error.name # => :doesnt_exist end

* / 4 * % & 5 ) &
* / * 5 * " - * ; & 3 module DidYouMean class ANameChecker include SpellCheckable def initialize(exception) @name = exception.name # user input @names = ???? # dictionary end end end

NameError NoMethodError 6OJOJUJBMJ[FEDPOTUBOU ClassNameChecker VariableNameChecker PUIFSFSSPST MethodNameChecker

. & 5 ) 0 % / " .
& 4 module DidYouMean class MethodNameChecker include SpellCheckable def initialize(no_method_error) # user input @name = no_method_error.name # dictionary @method_names = no_method_error.receiver.methods end end end

module DidYouMean class MethodNameChecker include SpellCheckable def initialize(no_method_error) # user
input @name = no_method_error.name # dictionary @method_names = no_method_error.receiver.methods end end end . & 5 ) 0 % / " . & 4

NameError#receiver R uby 2.3! string = "receiver" begin string.doesnt_exist rescue
NameError => error error.receiver == string # => true end w 6TFEUPCFJNQMFNFOUFEBTB$FYUFOTJPO w *TOPXQBSUPG3VCZ w 3FUVSOTUIFSFDFJWFSXIFSFUIFNFUIPEJTDBMMFEPO

. & 5 ) 0 % / " .
& 4 module DidYouMean class MethodNameChecker include SpellCheckable def initialize(no_method_error) # user input @name = no_method_error.name # dictionary @method_names = no_method_error.receiver.methods end end end

. & 5 ) 0 % / " .
& 4 module DidYouMean class MethodNameChecker include SpellCheckable def initialize(no_method_error) # user input @name = no_method_error.name # dictionary @method_names = no_method_error.receiver.methods end def candidates { @name => @method_names } end end end

NameError NoMethodError 6OJOJUJBMJ[FEDPOTUBOU ClassNameChecker VariableNameChecker PUIFSFSSPST MethodNameChecker ✅

7" 3 * " # - & / "
. & 4 module DidYouMean class VariableNameChecker include SpellCheckable def initialize(name_error) # user input @name = name_error.name.to_s # dictionary r = name_error.receiver @method_names = r.methods + r.private_methods @ivar_names = r.instance_variables @cvar_names = r.class.class_variables @cvar_names += r.class_variables if r.kind_of?(Module) @lvar_names = name_error.local_variables end def candidates { @name => (@lvar_names + @method_names + @ivar_names + @cvar_names) } end end end

NameError NoMethodError 6OJOJUJBMJ[FEDPOTUBOU ClassNameChecker VariableNameChecker PUIFSFSSPST MethodNameChecker ✅ ✅

$ - " 4 4 / " . &
4 module DidYouMean class ClassNameChecker include SpellCheckable def initialize(exception) @class_name, @receiver = exception.name, exception.receiver end def candidates { @class_name => class_names } end # generates a dictionary def class_names scopes.flat_map do |scope| scope.constants.map do |constant| scope == Object ? constant : "#{scope}::#{constant}" end end end def scopes @receiver.to_s.split("::").inject([Object]) do |_scopes, scope| _scopes << _scopes.last.const_get(scope) end.uniq end end end

module DidYouMean class ClassNameChecker include SpellCheckable def initialize(exception) @class_name, @receiver
= exception.name, exception.receiver end def candidates { @class_name => class_names } end # generates a dictionary def class_names scopes.flat_map do |scope| scope.constants.map do |constant| scope == Object ? constant : "#{scope}::#{constant}" end end end def scopes @receiver.to_s.split("::").inject([Object]) do |_scopes, scope| _scopes << _scopes.last.const_get(scope) end.uniq end end end $ - " 4 4 / " . & 4 5-%3

$ - " 4 4 / " . &
4 ... class Person ... def address Address.new(raw_address) end class Address ... def zipcode ZipCode.new(raw_zipcode) # => NameError end class Zipcode ... end end end

$ - " 4 4 / " . &
4 ... class Person ... def address Address.new(raw_address) end class Address ... def zipcode ZipCode.new(raw_zipcode) # => NameError end class Zipcode ... end end end Object.constants Person.constants Address.constants

$ - " 4 4 / " . &
4 ... class Person ... def address Address.new(raw_address) end class Address ... def zipcode ZipCode.new(raw_zipcode) # => NameError end class Zipcode ... end end end + + Object.constants Person.constants Address.constants

NameError NoMethodError 6OJOJUJBMJ[FEDPOTUBOU ClassNameChecker VariableNameChecker PUIFSFSSPST MethodNameChecker ✅ ✅ ✅

w /BNF&SSPS w /P.FUIPE&SSPS 4QFMMDIFDLFS 6TFSJOQVU %JDUJPOBSZ “Did you mean?
…” ✅ ✅

" T Q F M M D I
F D L F S . P O L F Z Q B U D I F T ✅ ✅

https://rubygems.org/gems/did_you_mean did_you_mean 1.0.0.rc1 N ow available!

3VCZXJMMTIJQXJUIdid_you_mean C om ing soon!

5 ) " / , 4

Saving People from Typos

Saving People from Typos

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