How do you add an array to another array in Ruby and not end up with a multi-dimensional result?

ruby arrays multidimensional-array
ncvncvn picture ncvncvn · Nov 26, 2009 · Viewed 392.8k times · Source 
somearray = ["some", "thing"]

anotherarray = ["another", "thing"]

somearray.push(anotherarray.flatten!)

I expected

["some","thing","another","thing"]

Answer

pilcrow picture pilcrow · Nov 26, 2009

You've got a workable idea, but the #flatten! is in the wrong place -- it flattens its receiver, so you could use it to turn [1, 2, ['foo', 'bar']] into [1,2,'foo','bar'].

I'm doubtless forgetting some approaches, but you can concatenate:

a1.concat a2
a1 + a2              # creates a new array, as does a1 += a2

or prepend/append:

a1.push(*a2)         # note the asterisk
a2.unshift(*a1)      # note the asterisk, and that a2 is the receiver

or splice:

a1[a1.length, 0] = a2
a1[a1.length..0] = a2
a1.insert(a1.length, *a2)

or append and flatten:

(a1 << a2).flatten!  # a call to #flatten instead would return a new array

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