Replace every item in an array with an empty item

Question

This is admittedly a bit of an odd issue, but I need to basically empty every item in an array (but keep the item itself).

For instance, if I have this array: [ 0, 5, 4, 7, 1 ]

I need to change it to: [ '', '', '', '', '']

I'm using Ruby 1.9.3.

Some charting software I'm using requires an array for labels and the only way to hide those labels is to make the corresponding items blank. Yes, lame.

Has to be an in-place operation? (note that you lose referential transparency on whatever method does that) — tokland
– tokland, Commented Jul 30, 2013 at 21:02
Can you clarify "but keep the item itself"? Do you mean "I want to return the result of performing the function on a variable without changing the value of the underlying variable"? If so, see my answer below! — Aaron Cronin
– Aaron Cronin, Commented Jul 30, 2013 at 21:04

Aaron Cronin · Accepted Answer · 2013-07-30 21:01:25Z

5

Enumerable#map replaces every element with the result of calling a block:

array = [ 0, 5, 4, 7, 1 ]
array.map { '' }
#=> ['', '', '', '', '']

If you wanted to mutate the original (if I understand your question this is precisely what you do NOT want to do), then use #map!

array.map! { '' }
array
#=> ['', '', '', '', '']

answered Jul 30, 2013 at 21:01

Aaron Cronin

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3 Comments

mu is too short Over a year ago

There's also Array.new(n, '') and Array.new(n) { '' } (which version you use depends on what's happening to the array). And there's always [''] * n (which suffers from the same problems as Array.new(n, '')).

Aaron Cronin Over a year ago

Also [''] * n will produce an n element array with every element being ''. So [''] * array.count would give the same result (but is slightly less clean IMO).

Aaron Cronin Over a year ago

Typical stackoverflow race condition ;)

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