Today I started programming in ruby.
Here’s what I managed to do so far:
string = Dir.entries(".")
string.delete_at(0)
string.delete_at(0)
- I get a list of files
2-3. I delete the first two elements (’.’ and ‘…’)
Now my files are all like “something - some other thing”
I want to split them:
string.each do |s|
puts s.split("-")[0]
end
So it outputs the “something” part in my filenames.
Now I’d like to remove duplicate entries (.uniq method right?).
Can it be done in a single line? If not, how do i get an array
containing only the “something” part to work on with .uniq?
I tried with some loops, to create a new array with the splitted string
in it, but my PHP approach doesn’t work:
i = 0
for i in string
splitted[i] = i.split("-")[0]
i += 1
end
Thank you!
On Sunday 25 May 2008, koichirose wrote:
Now my files are all like “something - some other thing”
I tried with some loops, to create a new array with the splitted string
in it, but my PHP approach doesn’t work:
i = 0
for i in string
splitted[i] = i.split("-")[0]
i += 1
end
Thank you!
If I understand you correctly, this (untested) should do what you want:
Dir.entries(’.’)[2…-1].map{|f| f.split(’-’)[0]}.uniq
Dir.entries(’.’)[2…-1]
returns an array containing all the contents of the current directory
except
the first two entries (actually, the [] method of an array, when called
with a
range returns all the elements of the array from the first index to the
last.
Since negative indexes count from right to left, with the rigthmost
element
having index -1, here you get all the entries from 2 to the last). This
avoids
the two calls to delete_at.
Then map is called on the array with the names of the files. Array#map
passes
each element of the array to the block and returns an array containing
the
values returned by the block for each element. In this case, each
element is a
string of the form ‘something-something_else’. The block splits the name
of
the file on the ‘-’ character, then takes (and implicitly returns) the
first
half (thanks to the [0]). This means that map returns an array
containing all
the first parts of the file names (the ones you want).
After that, we call uniq on the array, creating a new array without
duplicates.
I hope this helps
Stefano
On May 25, 3:17 pm, koichirose [email protected] wrote:
Now my files are all like “something - some other thing”
I tried with some loops, to create a new array with the splitted string
in it, but my PHP approach doesn’t work:
i = 0
for i in string
splitted[i] = i.split(“-”)[0]
i += 1
end
Thank you!
One way would be to use Dir.glob:
unique_array = Dir.glob(‘-’).map {|f| f.split(‘-’)[0]}.uniq
Then you only get filenames that have - in them.
Or:
unique_array = Dir.entries(‘.’)[2…-1].map {|f| f.split(‘-’)[0]}.uniq
But starting from here:
string = Dir.entries(“.”)
string.delete_at(0)
string.delete_at(0)
string.map! {|f| f.split(‘-’)[0]}.uniq!
yermej wrote:
unique_array = Dir.entries(’.’)[2…-1].map {|f| f.split(’-’)[0]}.uniq
string.map! {|f| f.split(’-’)[0]}.uniq!
What if I do:
Dir.entries(’.’)[2…-1].map! {|f| f.split(’-’)[0]}.uniq
with map! instead of map ?
I’d now have Dir.entries trimmed, splitted and “uniqed” ?
Thanks
yermej wrote:
unique_array = Dir.entries(‘.’)[2…-1].map {|f| f.split(‘-’)[0]}.uniq
string.map! {|f| f.split(‘-’)[0]}.uniq!
What if I do:
Dir.entries(‘.’)[2…-1].map! {|f| f.split(‘-’)[0]}.uniq
with map! instead of map ?
map! changes the array it’s called on. since that is a temporary array
returned by Dir.entries[2…-1] which is discarded after map! that won’t
work.
mfg, simon … l
It works! I see that .uniq is case-sensitive (something else !=
something Else). Can I avoid that?
Yes, just convert it to lower case before the uniq:
Dir.entries(‘.’)[2…-1].map{|f| f.split(‘-’)[0].lower}.uniq
mfg, simon … l
Stefano C. wrote:
I think you mean downcase, not lower.
Yes, .downcase, confirmed
On Monday 26 May 2008, Simon K. wrote:
Dir.entries(’.’)[2…-1].map{|f| f.split(’-’)[0].lower}.uniq
I think you mean downcase, not lower.
Stefano
koichirose wrote:
It returns: hello.rb:7: undefined method `capitalize’ for nil:NilClass
(NoMethodError)
That error message means you’re trying to call the capitalize method on
something that doesn’t exist. I.e. xxx.capitalise where xxx evaluates to
nil. The class NilClass doesn’t have a capitalize method. Your problem
is with xxx; trying “p”-ing it.
koichirose wrote:
Yes, .downcase, confirmed
I have a problem, why does this work:
list = Dir.entries(’.’)[2…-1].map{|f| f.split(’ - ')[0].capitalize}
And this doesn’t?
list2 = Dir.entries(’.’)[2…-1].map{|f| f.split(’ - ')[1].capitalize}
It returns: hello.rb:7: undefined method capitalize' for nil:NilClass (NoMethodError) from hello.rb:7:inmap’
Thank you
Dave B. wrote:
That error message means you’re trying to call the capitalize method on
something that doesn’t exist. I.e. xxx.capitalise where xxx evaluates to
nil. The class NilClass doesn’t have a capitalize method. Your problem
is with xxx; trying “p”-ing it.
Ok, but those 2 lines are the same, except that with list2 I take the
part after ’ - '.
If I do:
#~ j=0
#~ for i in list2
#~ puts list2[j]
#~ j +=1
#~ end
it works. Why are list and list2 behaving differently?
On Tue, May 27, 2008 at 12:14 PM, koichirose [email protected] wrote:
Dave B. wrote:
Ok, but those 2 lines are the same, except that with list2 I take the part
after ’ - '.
If I do:
#~ j=0
#~ for i in list2
#~ puts list2[j]
#~ j +=1
#~ end
You have entries that either have no dash “-”, or have one but nothing
after. You can NilClass#puts, but not just any method on it, such as
#capitalize. If you don’t need them (like, for example, counting
purposes), remove your nils out of the array list with #compact.
Example in irb…
[1, nil, 2].compact
=> [1, 2]
Todd