Removing duplicates and substrings from an array

Ruby
1

I’ve got an array of strings, say like:

[“Bob”, “John”, “Bobby”, “John”]

I want to remove duplicates and elements that are substrings of other
elements. Therefore, the above array would become:

[“John”,“Bobby”]

(order doesn’t really matter to me, BTW)

Right now, this is what I’m doing:

def remove_duplicates_and_subsequences(some_array)
result = []
some_array.each_index do |i|
(some_array.length-1).downto 0 do |j|
some_array.delete_at(j) if i != j &&
some_array[i].index(some_array[j])
end
end
return result
end

Is there a better way to do that? I feel like I should be using select
or
reject, but can’t think of a way to do it.

Thanks,
Sammy L.

2

Sam L. wrote:

I’ve got an array of strings, say like:

[“Bob”, “John”, “Bobby”, “John”]

I want to remove duplicates and elements that are substrings of other
elements. Therefore, the above array would become:

[“John”,“Bobby”]

[“Bob”, “John”, “Bobby”, “John”].uniq!

(or uniq )

3

Sam L. wrote:

I’ve got an array of strings, say like:

[“Bob”, “John”, “Bobby”, “John”]

I want to remove duplicates and elements that are substrings of other
elements. Therefore, the above array would become:

[“John”,“Bobby”]

(order doesn’t really matter to me, BTW)

Right now, this is what I’m doing:

def remove_duplicates_and_subsequences(some_array)
result = []
some_array.each_index do |i|
(some_array.length-1).downto 0 do |j|
some_array.delete_at(j) if i != j &&
some_array[i].index(some_array[j])
end
end
return result
end

Is there a better way to do that? I feel like I should be using select
or
reject, but can’t think of a way to do it.

Thanks,
Sammy L.

You tried to use the method uniq?

[1,2,3,4,1,3].uniq => [1,2,3,4]

4

On Nov 26, 2007 10:15 AM, Sam L. [email protected] wrote:

return result

end

Is there a better way to do that? I feel like I should be using select or
reject, but can’t think of a way to do it.

Thanks,
Sammy L.

You can use Array.uniq to remove duplicates. For removing words that
are contained in other words, I would sort the array, then for each
string in the array:

good_strings = []
0.upto(good_strings.length - 2) do |i|
good_strings << strings[i] unless strings[i + 1].include?(strings[i])
end

…or something like that.

5

On Nov 26, 9:15 am, Sam L. [email protected] wrote:

    end
end
return result

end

Is there a better way to do that? I feel like I should be using select or
reject, but can’t think of a way to do it.

Thanks,
Sammy L.

This should work:

arr = [“Bob”, “John”, “Bobby”, “John”]
arr.uniq!
arr.reject {|a| arr.any? {|b| b != a and b =~ /#{a}/}}

Jeremy

6

I think there could also be a .map solution but I cant figure it out
right now, .uniq just really seems the most simple and elegant for this
given problem at hand

7

yermej wrote the following on 26.11.2007 18:15 :

[“John”,“Bobby”]
This should work:

arr = [“Bob”, “John”, “Bobby”, “John”]
arr.uniq!
arr.reject {|a| arr.any? {|b| b != a and b =~ /#{a}/}}

You’ll have surprises if there’s a “.” element…

arr = [“Bob”, “John”, “Bobby”, “John”]
arr.uniq!
arr.reject {|a| arr.any? {|b| b != a and a.index(b) } }

seems safer and quicker to me.

Lionel

8

Lionel B. wrote the following on 26.11.2007 18:20 :

You’ll have surprises if there’s a “.” element…

arr = [“Bob”, “John”, “Bobby”, “John”]
arr.uniq!
arr.reject {|a| arr.any? {|b| b != a and a.index(b) } }

Oups: I misread the question.

It should be b.index(a) (I rejected the superstrings instead of the
substrings).

Lionel

9

Lionel B. wrote:

arr.reject {|a| arr.any? {|b| b != a and a.index(b) } }

I’d make that index into include? because you don’t really care about
the
index here.

10

On Nov 26, 11:20 am, Lionel B. [email protected]
wrote:

[“Bob”, “John”, “Bobby”, “John”]

You’ll have surprises if there’s a “.” element…

arr = [“Bob”, “John”, “Bobby”, “John”]
arr.uniq!
arr.reject {|a| arr.any? {|b| b != a and a.index(b) } }

seems safer and quicker to me.

Lionel

Good point. Thank you.

Jeremy

11

Sebastian H. wrote the following on 26.11.2007 18:27 :

Lionel B. wrote:

arr.reject {|a| arr.any? {|b| b != a and a.index(b) } }

I’d make that index into include? because you don’t really care about the
index here.

I agree, the code is then easier to read too.

Lionel

12

Everyone,

On Nov 26, 2007 11:51 AM, Lionel B.
[email protected]
wrote:

I agree, the code is then easier to read too.

That’s precisely what I was looking for (or felt like I should be
doing).
Thanks to all for their help!

Sam