Pretty format arrays

Ruby
1

Hello,

I am using OptionParser and one of the nifty things it has is multi line
descriptions for each option. I have a particularly long list of valid
arguments for a valid option, for instance
cities=[London,Paris,NY…].
If printed in a single line it runs over and looks ugly. My hack so far
is:

def pretty_print_list list,num=5
a=[]
(0…list.size).step(num) { |i| a << (list[i…i+num]).join(’,’) }
a
end

This returns a list of strings which I pass as *list to the OptionParser
.on
method as follows:

arg.on("–city [CITY]",cities,*list) { |o| options.city=o }

The hack works fine, but on a broader subject, is there a nice easy way
of
grouping arrays? In python Range accepts a step value which is quite
awesome…

Thanks,

Jayanth

2

2009/4/15 Srijayanth S. [email protected]:

a
end

This returns a list of strings which I pass as *list to the OptionParser .on
method as follows:

arg.on(“–city [CITY]”,cities,*list) { |o| options.city=o }

The hack works fine, but on a broader subject, is there a nice easy way of
grouping arrays? In python Range accepts a step value which is quite
awesome…

#each_slice does the job:

irb(main):008:0> a = (1…10).to_a
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
irb(main):009:0> a.each_slice(3).to_a
=> [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10]]

Cheers

robert

3

On Wed, Apr 15, 2009 at 9:24 AM, Srijayanth S.
[email protected] wrote:

The hack works fine, but on a broader subject, is there a nice easy way of
grouping arrays?

You could use Enumerator#each_slice:

require 'enumerator'

def pretty_print_list(list, num=5)
  a = []
  list.each_slice(5) {|s| a << s.join(",") }
  a
end

Hope this helps,

Lyle