Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 8 years ago.
Improve this question
When creating a new array in IRB, I can use Array.new to get an empty, unassigned array.
Is there a way to reassign that new array? Can I turn, [] into a variable named my_new_array?
I know I can do this:
my_new_array = Array.new
Or I can do:
my_other_new_array = []
But what about reassigning Array.new?
I'm new to Ruby and I'm curious about this little nuance.
In IRB, the underscore _ method will give you the results of the last expression:
Array.new
# => []
my_new_array = _
# => []
Array.new(2, "foo")
# => ["foo", "foo"]
my_new_array = _
# => ["foo", "foo"]
Related
Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 5 years ago.
Improve this question
I have got a list l = [:foo, :bar, :baz] and want to assign a varible into a hash h ={} programmatically.
Hash should look like
{ foo: { bar: { baz: some_value } } }
Note: the keys are variables!
Question:
How can I do this?
You could use inject on the reversed list :
l = [:foo, :bar, :baz]
h = l.reverse.inject(:some_value) do |value, key|
{ key => value }
end
p h
# {:foo=>{:bar=>{:baz=>:some_value}}}
reverse is used in order to build the innermost hash first, and keep building the nested hash outwards.
Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 8 years ago.
Improve this question
I got this tab :
["aaaaaaaaaaaaaaaaaaa",
"15/87/2014r",
"2453/NRc05",
"xxxxxxxxxxxxxxxxxxxxxxxxxx",
"Adaptée",
"09/12/2013",
"pub.pdf"]
And I only want "xxxxxxxxxxxxx" for example.
I found .next.element(s) but I got no idead of how to use it.. :/
Array#each returns an Enumerator:
arr = [1, 2, 3]
enum = arr.each
enum.next
#=> 1
enum.next
#=> 2
enum.next
#=> 3
enum.next
#=> StopIteration: iteration reached an end
Update
Regarding your comment
I have a array with some datas, and I wanted to save them in a hash with names like... {Name : aaaaa, First Name : bbbbbb} etc etc etc
Rather than calling next over and over again (I assume you are doing something like this):
data = ["John", "Doe"]
enum = data.each
hash = {}
hash[:first_name] = enum.next
hash[:last_name] = enum.next
# ...
You can combine two arrays with Array#zip and convert it to a hash using Array#to_h:
data = ["John", "Doe"]
keys = [:first_name, :last_name, :other]
keys.zip(data).to_h
#=> {:first_name=>"John", :last_name=>"Doe", :other=>nil}
Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 9 years ago.
Improve this question
Here is my sample code
:key1 => "a"
:key2 => "b"
:key3 => "c"
array1 = [[:key1, :key1, :key1],[:key1, :key2, :key3],[:key2, :key2, :key1]]
array1.each { |x| if x.sym_tos == "a"
puts "All match!"
else
puts "no match"
end
}
Yet when I run it, I get the following error code:
undefined method `sym_to_s' for [:R1C1, :R1C2, :R1C3]:Array (NoMethodError)
You probably wanted to say
if x.uniq.length == 1
Closed. This question needs details or clarity. It is not currently accepting answers.
Want to improve this question? Add details and clarify the problem by editing this post.
Closed 9 years ago.
Improve this question
I have this array which I would like to copy and change an element's value. How can I do it (Ruby 1.9.3p429)
a = Array.new(2,"test") #a => ["test","test"] #a.object_id => 21519600 #a[0].object_id => 21519612
b = a.clone #b => ["test","test"] #b.object_id => 22940520 #b[0].object_id => 21519612
c = a.dup #c => ["test","test"] #c.object_id => 22865176 #c[0].object_id => 21519612
d = Array.new(a) #d => ["test","test"] #c.object_id => 23179224 #d[0].object_id => 21519612
c[0].upcase! #produces #a => ["TEST","TEST"], #b => ["TEST","TEST"], #c => ["TEST","TEST"] ...`
In Ruby every object is actually a reference to object so if you have array
x = [a, b, c, d]
and copy it into another array
y = x.clone
it will copy references to original objects, not objects themselves.
To do exactly what you want you would have to copy objects in a loop, however you're too focused on how you want to achieve array copying, instead of achieving your ultimate goal, get a new array which consists of upcased items of the original array.
Explore the Enumerable module and you will find things like #map, #select, #inject, etc. For instance this is how you get a copy of array with all names upcased:
["test", "test"].map { |element| element.upcase }
From your comment, you seem to want to upcase "c[0] only". I don't understand why you need to capitalize via a duplicate of a, but here is how to do it.
a = Array.new(2){"test"}
c = a.dup
c[0].upcase!
a # => ["TEST", "test"]
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
Questions asking for code must demonstrate a minimal understanding of the problem being solved. Include attempted solutions, why they didn't work, and the expected results. See also: Stack Overflow question checklist
Closed 9 years ago.
Improve this question
For example,I have datas:
a,b,c,a,c,d
I want to get different datas: a,b,c,d
I want to get data count: a => 2,b => 1,c => 2,d => 1
There may have other datas,such as e,f,g,etc.
How to do?
a = [:a,:b,:c,:a,:c,:d]
p h = a.each_with_object(Hash.new(0)){|i,h| h[i] += 1}
p h.keys
# >> {:a=>2, :b=>1, :c=>2, :d=>1}
# >> [:a, :b, :c, :d]