Reputation: 901
I have an array with unique elements. Is there a way to replace a certain value in it with another value without using its index value?
Examples:
array = [1,2,3,4]
if array.include? 4
# "replace 4 with 'Z'"
end
array #=> [1,2,3,'Z']
hash = {"One" => [1,2,3,4]}
if hash["One"].include? 4
# "replace 4 with 'Z'"
end
hash #=> {"One" => [1,2,3,'Z']}
Upvotes: 27
Views: 63888
Reputation: 17030
A very simple solution that assumes there will be no duplicates and that the order doesn't matter:
hash = { 'One' => [1, 2, 3, 4] }
hash['One'].instance_eval { push 'Z' if delete 4 }
instance_eval
sets the value of self
to the receiver (in this case, the array [1,2,3,4]
) for the duration of the block passed to it.
Upvotes: 2
Reputation: 168269
You can do it as:
array[array.index(4)] = "Z"
If the element is not necessarily in the array, then
if i = array.index(4)
array[i] = "Z"
end
Upvotes: 20
Reputation: 108269
You can use Array#map
array = array.map do |e|
if e == 4
'Z'
else
e
end
end
to edit the array in place, rather than creating a new array, use Array#map!
If you have more than one thing you want to replace, you can use a hash to map old to new:
replacements = {
4 => 'Z',
5 => 'five',
}
array = array.map do |e|
replacements.fetch(e, e)
end
This make uses of a feature of Hash#fetch, where if the key is not found, the second argument is used as a default.
Upvotes: 11