Ruby class Hash | Chautauqua

Creating

# h = { a: 1, b: 2, c: 3 }

Methods

Creating a Hash

[]Hash[h] # {a: 1,b: 2,c: 3} Documentation Playground

h = { a: 1, b: 2, c: 3 }
Hash[h].inspect

{a: 1, b: 2, c: 3}

newHash.new # {} Documentation Playground

Hash.new.inspect

{}

try_convertHash.try_convert('string') # nil Documentation Playground

Hash.try_convert('string').inspect

nil

Setting Hash state

compare_by_identityh.compare_by_identity;h['a']… # {'a':1,'a':2} Documentation Playground

h={}; h.compare_by_identity; h[:a]=1;h[:a]=2
h.inspect

{"a" => 1, "a" => 2}

compare_by_identity?h.compare_by_identity? # true Documentation Playground

h={}; h.compare_by_identity; h.compare_by_identity?

true

defaulth={};h.default=false;h.default # false Documentation Playground

h={};h.default=false;h.default

false

default_proch={};(h.default_proc=proc{|h|…}).class # Proc Documentation Playground

h={}; h.default_proc=proc {|h, k| k }; h.default_proc.class

Proc

rehashh={[1]=>'a'};…;h[[1, 2]];h.rehash # nil,a Documentation Playground

h={[1] => 'a'}; k=h.keys.first; k << 2; h[[1, 2]]
h.rehash; h[[1, 2]]; h.inspect

{[1, 2] => "a"}

Querying

any?h.any?([:a, 1]; h.any?{|k,v| v<3} # true Documentation Playground

h = { a: 1, b: 2, c: 3 }; h.any?([:a, 1])

true

empty?h={};h.empty? # true Documentation Playground

h={}; h.empty?

true

eql?h1={a:1};h2={a:1};h1.eql? h2 # true Documentation Playground

h1={a:1,b:2}; h2={a:1,b:2}; h1.eql? h2

true

hashh.hash # 6345789 (differs) Documentation Playground

h={a:1,b:2}; h.hash

value? (al… has_value?)h.value?(1) # true Documentation Playground

h = { a: 1, b: 2, c: 3 }; h.value?(1)

true

key? (alias include? member? has_key?)h.key?(:a) # true Documentation Playground

h = { a: 1, b: 2, c: 3 }; h.key?(:a)

true

size (alias length))h.size # 3 Documentation Playground

h = { a: 1, b: 2, c: 3 }; h.size

3

Comparing

<h={a:1}; h<{a:1,b:2} # true Documentation Playground

h={a:1}; h<{a:1,b:2}

true

<=h={a:1,b:2}; h<={a:1,b:2} # true Documentation Playground

h={a:1,b:2}; h<={a:1,b:2}

true

==h={a:1,b:2}; h=={a:1,b:2} # true Documentation Playground

h={a:1,b:2}; h<{a:1,b:2}

true

>h={a:1,b:2}; h>{a:1} # true Documentation Playground

h={a:1,b:2}; h>{a:1}

true

>=h={a:1,b:2}; h<={a:1,b:2} # true Documentation Playground

h={a:1,b:2}; h<={a:1,b:2}

true

Fetching

[]h[:b] # 2 Documentation Playground

h = { a: 1, b: 2, c: 3 }
h[:b]

2

assoch.assoc(:b) # [:b,2] Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.assoc(:b)

[:b, 2]

rassoch.rassoc(2) # [:b,2] Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.rassoc(2)

[:b, 2]

digh={a:{b:{c:3}}}; h.dig(:a) # {b:{c:3}} Documentation Playground

h = { a: { b: {c: 3}}}
h.dig(:a).inspect

{b: {c: 3}}

fetchh.fetch(:b) # 2 Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.fetch(:b)

2

fetch_valuesh.fetch_values(:b,:c) # [2,3] Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.fetch_values(:b, :c)

[2, 3]

keyh.key(2) # :b Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.key(2).inspect

:b

keysh.keys # [:a,:b,:c] Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.keys.inspect

[:a, :b, :c]

valuesh.values # [1,2,3] Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.values.inspect

[1, 2, 3]

values_ath.values_at(:a,:c) # [1,3] Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.values_at(:a, :c).inspect

[1, 3]

Assigning

[] (alias store)h[:b]=7; h.store(:b,7) # {a:1,b:7,c:3} Documentation Playground

h = { a: 1, b: 2, c: 3 }
h[:b] = 7; h.inspect

{a: 1, b: 7, c: 3}

mergea={a:1}; b={b:2}; b.merge(a,b) # {a:1,b:2} Documentation Playground

h1 = {a:1, b:2}; h2 = {b:2, c:3}
h1.merge(h1, h2).inspect

{a: 1, b: 2, c: 3}

update (alias merge!)a={a:1,b:2}; b={a:7}; a.update(b) # {a:7,…} Documentation Playground

h1 = {a:1, b:2}; h2 = {a:7}
h1.update(h2).inspect

{a: 7, b: 2}

replace (alias initialize_copy)a={a:1,b:2}; a.replace(a:7,c:8) # {a:7,c:8} Documentation Playground

h1 = {a:1, b:2}; h2 = {a:7, c:8}
h1.replace(h2).inspect

{a: 7, c: 8}

Deleting

clearh.clear # {} Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.clear.inspect

{}

compact!{a:1,b:nil,c:3}.compact # {a:1,c:3} Documentation Playground

h = { a: 1, b: nil, c: 3 }
h.compact.inspect

{a: 1, c: 3}

deleteh.delete(:b) # 2; {a:1,c:3} Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.delete(:b); h.inspect

{a: 1, c: 3}

select (alias filter)!h.select {|k,v| v<3} # {a:1mb:2} Documentation Playground

h = { a: 1, b: 2, c: 3, d: 4 }
h.select {|k,v| v<3}.inspect

{a: 1, b: 2, d: 4}

delete_ifh.delete_if {|k,v| v<3} # {c:3} Documentation Playground

h = { a: 1, b: 2, c: 3, d: 4 }
h.delete_if {|k,v| v<3}; h.inspect

{c: 3, d: 4}

keep_ifh.keep_if {|k,v| v<3} # {a:1,b:2} Documentation Playground

h = { a: 1, b: 2, c: 3, d: 4 }
h.keep_if {|k,v| v<3}; h.inspect

{a: 1, b: 2}

reject!h.reject {|k,v| k[0]=='b'} # {a:1,c:3} Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.reject {|k,v| k[0]=='b'}.inspect

{a: 1, c: 3}

shifth.shift # [:a,1]; {b:2,c:3} Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.shift; h.inspect

{b: 2, c: 3}

sliceh.slice(:b,:c) # {b:2,c:3} Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.slice(:b,:c).inspect

{b: 2, c: 3}

! See non-bang methods for:

compact! select!→(alias filter) reject

Iterating

each (alias each_pair)h.each {|k,v| p "#{k}-#{v}"} # a-1;b-2;c-3 Documentation Playground

s=''; h = { a: 1, b: 2, c: 3 }
; h.each {|k,v| s+="#{k}-#{v}|"}; s

a-1|b-2|c-3|

each_keyh.each_key {|k| p "#{k}"} # a;b;c Documentation Playground

s=''; h = { a: 1, b: 2, c: 3 }
; h.each_key {|k| s+="#{k}|"}; s

a|b|c|

each_valueh.each_value {|v| p "#{v}"} # 1;2;3 Documentation Playground

s=''; h = { a: 1, b: 2, c: 3 }
; h.each_value {|k| s+="#{k}|"}; s

1|2|3|

Converting

flattenh3={a:1,d:[:e]}.flatten(2) # [:a,1,:d,:e] Documentation Playground

h = {a: {b: 1, c: 2}, d: [:e, [:f, [:g]]]}
h.flatten(3)

[:a, {b: 1, c: 2}, :d, :e, :f, [:g]]

to_s (alias inspect)h.to_s # "[:a,1,:d,:e]" Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.to_s

"{a: 1, b: 2, c: 3}"

to_ah.to_a # [[:a,1],[:b,2],[:c,3]] Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.to_a

[[:a, 1], [:b, 2], [:c, 3]]

to_hash{a:1,b:2,:c=>3}.to_hash # {a:1,b:2,c:3} Documentation Playground

h = { a: 1, b: 2, :c => 3 }
h.to_hash.inspect

{a: 1, b: 2, c: 3}

to_proch.to_proc.class # Proc Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.to_proc.class.inspect

{a: 1, b: 2, c: 3}

Transforming Keys and Values

inverth.invert # {1 => :a,2 => :b,3 => :c} Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.invert.inspect

{1 => :a, 2 => :b, 3 => :c}

transform_keys!h.transform_keys{|k|k.to_s} # {'a'=>1,'b'=>…} Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.transform_keys {|k| k.to_s}.inspect

{"a" => 1, "b" => 2, "c" => 3}

transform_values!h.transform_values{|v|v+5} # {a:6,b:7,c:8} Documentation Playground

h = { a: 1, b: 2, c: 3 }
h.transform_values {|v| v + 10}.inspect

{a: 11, b: 12, c: 13}

! See non-bang methods for:

transform_keys! transform_values!

Ruby class Hash interactive

Creating

Methods

Creating a Hash

Setting Hash state

Querying

Comparing

Fetching

Assigning

Deleting

Iterating

Converting

Transforming Keys and Values