I have a ruby array of, say, 10 elements, and I'd like to return all but the 5th element.
a = *(1..10) I'd like to be able to do something like
a[0..3 + 5..9] Or even better something like (borrowing from the R syntax),
a[-4] to do this, but that doesn't work. (Nor does anything more clever I've tried like getting an array of the element indices). What's the best way to do this in ruby?
You can use values_at: http://www.ruby-doc.org/core-1.9.3/Array.html#method-i-values_at
so you may use it as
a.values_at(0..3, 5..9) No black magic required:
a[0..3] + a[5..9] Look in the documentation under Array#delete_at
For example, myarray.delete_at(5) results in the array lacking what was element 5 (counting from 0, of course).
Example:
class Array def without(n) self.delete_at(n) return self end end arr = [1, 2, 3, 4] p arr.without(1) #=> [1, 3, 4] However, as a commenter points out, this alters the original array, which may not be what the O.P. wants! If that's an issue, write it like this:
class Array def without(n) arr2 = Array.new(self) arr2.delete_at(n) return arr2 end end That returns the desired array (an array lacking the nth element of the original) while leaving the original array untouched.
p arr.without(1) #=> [1, 3, 4]; p arr #=> [1, 3, 4] unfortunately because delete_at changes the original array.
a[0..3] + a[5..9]?(1..10).reject { |element| element == 5 })