Split an array of object by first letter

Ruby
1

Hi,
I have an array of brands and I need to split this array by brand name
first letter. How can I do that?

Greg

2

Greg Ma wrote:

Hi,
I have an array of brands and I need to split this array by brand name
first letter. How can I do that?

[“fz”, “yt”, “fu”, “za”, “zw”, “yo”, “zb”].group_by {|s|s[0,1]}
=> {“y”=>[“yt”, “yo”], “z”=>[“za”, “zw”, “zb”], “f”=>[“fz”, “fu”]}

3

On Jun 10, 1:45 pm, Joel VanderWerf [email protected] wrote:

I have an array of brands and I need to split this array by brand name
first letter. How can I do that?

[“fz”, “yt”, “fu”, “za”, “zw”, “yo”, “zb”].group_by {|s|s[0,1]}
=> {“y”=>[“yt”, “yo”], “z”=>[“za”, “zw”, “zb”], “f”=>[“fz”, “fu”]}

Joel is right on. My addition below shows that (a) this works not just
for two-letter words, and (b) if you’re using Ruby 1.9, you can use a
slightly simpler syntax:

[ “foo”, “bar”, “flim”, “bork”, “cow” ].group_by{ |name| name[0] }
#=> {“f”=>[“foo”, “flim”], “b”=>[“bar”, “bork”], “c”=>[“cow”]}

Note that case matters, but you can make it irrelevant:

[ “foo”, “bar”, “Flim”, “bork” ].group_by{ |name| name[0] }
#=> {“f”=>[“foo”], “b”=>[“bar”, “bork”], “F”=>[“Flim”]}

[ “foo”, “bar”, “Flim”, “bork” ].group_by{ |name| name[0].downcase }
#=> {“f”=>[“foo”, “Flim”], “b”=>[“bar”, “bork”]}

And finally, just for the love of monkeypatching:

class String
def first_letter
self[0].downcase
end
end

class Array
def alphabetical
Hash[ group_by{|s|s.first_letter}.sort_by{|c,a|c} ]
end
end

[ “foo”, “bar”, “Flim”, “bork” ].alphabetical
#=> {“b”=>[“bar”, “bork”], “f”=>[“foo”, “Flim”]}

4

Wes B. wrote:

Anyone remember %w or do you all love quotes so much :stuck_out_tongue:

%w/:-/

(Actually, it’s finger memory from using non-ruby languages.)

Since the poster didn’t specify whether they were on ruby 1.8 or 1.9:

#group_by is available in 1.8.7

5

----- “Joel VanderWerf” [email protected] wrote:

Wes B. wrote:

Anyone remember %w or do you all love quotes so much :stuck_out_tongue:

%w/:-/

(Actually, it’s finger memory from using non-ruby languages.)

Finger memory - Ha that is a good one that I have never heard before.

Since the poster didn’t specify whether they were on ruby 1.8 or
1.9:

#group_by is available in 1.8.7

One can never pass up an opportunity to use inject (j/k)! Seriously the
OP might not be on 1.8.7 yet so I threw it out there.

6

----- “Phrogz” [email protected] wrote:

for two-letter words, and (b) if you’re using Ruby 1.9, you can use a

class Array
def alphabetical
Hash[ group_by{|s|s.first_letter}.sort_by{|c,a|c} ]
end
end

[ “foo”, “bar”, “Flim”, “bork” ].alphabetical
#=> {“b”=>[“bar”, “bork”], “f”=>[“foo”, “Flim”]}

Anyone remember %w or do you all love quotes so much :stuck_out_tongue:

Since the poster didn’t specify whether they were on ruby 1.8 or 1.9:

irb(main):021:0> %w/foo bar Film bork Baz/.inject( {} ) { |h,v| k =
v[0,1].downcase; a = h[k] || []; h.merge( { k => a << v } ) }
=> {“b”=>[“bar”, “bork”, “Baz”], “f”=>[“foo”, “Film”]}