If array = [1, 2, 3, 4, 5, 6, 7, 8, 9],
I want to delete a range of elements from array.
For example: I want to delete all elements with an index in the range 2..5 from that array, the result should be [1, 2, 7, 8, 9]
Thanks in advance.
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2..5 is the index range not valuesGuna Sekhar– Guna Sekhar2014-11-13 12:58:47 +00:00Commented Nov 13, 2014 at 12:58
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Your question is unclear. What do you really want to do? Remove values at indices 2..5, which is 2,3,4, and 5? or you want to remove those values which matches on or between 2..5?Surya– Surya2014-11-13 13:05:24 +00:00Commented Nov 13, 2014 at 13:05
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5 Answers
Use slice!:
Deletes the element(s) given by [...] a range.
array = [1, 2, 3, 4, 5, 6, 7, 8, 9]
array.slice!(2..5)
array #=> [1, 2, 7, 8, 9]
4 Comments
Bala
Yours is sweet and simple. I almost forgot
slice!
Roman Kiselenko
This should include
2 and not include 5?
Stefan
@Зелёный indices 2..5 refer to values 3, 4, 5 and 6.
Cary Swoveland
Good solution, Stefan. I would be stunned well and truely if the downvoter came forward to defend his/her black mark.
You can try this
[1, 2, 3, 4, 5, 6, 7, 8, 9].reject.with_index{|element,index| index >= 2 && index <= 5}
=> [1, 2, 7, 8, 9]
or use delete_if
[1, 2, 3, 4, 5, 6, 7, 8, 9].delete_if.with_index{|element,index| index >= 2 && index <= 5}
=> [1, 2, 7, 8, 9]
Comments
As Stefan posted, use slice! to remove values located inside a certain range in the array. If what you need, however, is to remove values that are within a certain range use delete_if.
array = [9, 8, 7, 6, 5, 4, 3, 2, 1]
array.delete_if {|value| (2..5) === value }
array #=> [9, 8, 7, 6, 1]
Comments
Delete When Range Includes Value
One of the many ways to do this is to invoke Array#delete_if with a block that checks whether each element of the Array is included in the Range with Array#include?. For example:
array = [1, 2, 3, 4, 5, 6, 7, 8, 9]
array.delete_if { |i| (2..5).include? i }
#=> [1, 6, 7, 8, 9]
1 Comment
trushkevich
Why post two separate answers? There is an "edit" link.
Delete Array Elements by Index from Range
If you are trying to delete elements by index rather than by value, one way to solve this is to iterate over your Range object, invoking Array#delete_at for each index in the range. For example:
array = [1, 2, 3, 4, 5, 6, 7, 8, 9]
(2..5).map { |i| array.delete_at i }
##=> [3, 5, 7, 9]
2 Comments
trushkevich
Why post two separate answers? There is an "edit" link.
yuzhoul
This does not work, array.delete_at is mutating the array while you are iterating.