Concatenating the strings of 2 arrays into 1 array

Question

I read (in the documentation) how to concatenate the strings of one array with another string:

a = [ "a", "b", "c", "d" ]
a.collect! {|x| x + "!" }
a                          #=>  [ "a!", "b!", "c!", "d!" ]

but what I haven't figured out is how to concatenate the strings of 2 arrays into one. For example:

field_suffix = %w[prev curr]
field_names = %w[_first_name _last_name]

What I'd like to see is this:

["prev_first_name", "curr_first_name", "prev_last_name", "curr_last_name"]

The order doesn't matter. It could be:

["prev_first_name", "prev_last_name", "curr_first_name", "curr_last_name"]

Thanks for all the answers - they all work great. I accepted JavaNut13's answer because it was first but I actually went back and used megas answer because it seemed the 'sexiest'. I voted all the answers up because they all work. — purplerice
– purplerice, Commented Aug 25, 2012 at 11:47

megas · Accepted Answer · 2012-08-25 10:15:11Z

3

field_suffix.product(field_names).map(&:join)

answered Aug 25, 2012 at 10:15

megas

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Will Richardson · Accepted Answer · 2012-08-25 10:01:13Z

1

I would do it with the following:

out=[]
pre=["sub", "pre"]
suf=["less", "ness"]
pre.each do |p|
  suf.each do |s|
    out.push(p+s)
  end
end
puts out

Or in less lines:

out=[]
pre=["sub", "pre"]
suf=["less", "ness"]
pre.each{|p| suf.each{|s| out.push(p+s)}}

This will not return the array (sadly), you have to have the second array; out which will be subless, subness, preless, preness

edited Aug 25, 2012 at 10:01

answered Aug 25, 2012 at 9:53

Will Richardson

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2 Comments

purplerice Over a year ago

Thanks for the answer, unfortunately, this gives me out = ["sub","pre"]

Will Richardson Over a year ago

See answer, print out array

Incidently · Accepted Answer · 2012-08-25 10:06:47Z

1

Here it is:

field_suffix = %w[prev curr]
field_names = %w[_first_name _last_name]

result = field_suffix.product(field_names).collect {|suffix, name| suffix + name}

See Array#product for details

edited Aug 25, 2012 at 10:06

answered Aug 25, 2012 at 10:01

Incidently

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