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Searching a CSV file - beginner seeking help

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  Searching a CSV file - beginner seeking help Simon Harrison <simon@simonharrison.net> - 2011-04-01 13:38 -0500
    Re: Searching a CSV file - beginner seeking help Simon Harrison <simon@simonharrison.net> - 2011-04-01 16:05 -0500
    Re: Searching a CSV file - beginner seeking help Simon Harrison <simon@simonharrison.net> - 2011-04-01 16:26 -0500
      Re: Searching a CSV file - beginner seeking help Jesús Gabriel y Galán <jgabrielygalan@gmail.com> - 2011-04-01 16:45 -0500
    Re: Searching a CSV file - beginner seeking help Simon Harrison <simon@simonharrison.net> - 2011-04-01 15:55 -0500
    Re: Searching a CSV file - beginner seeking help Simon Harrison <simon@simonharrison.net> - 2011-04-02 02:39 -0500
      Re: Searching a CSV file - beginner seeking help marco <marcofognog@gmail.com> - 2011-04-02 05:44 -0700
    Re: Searching a CSV file - beginner seeking help Simon Harrison <simon@simonharrison.net> - 2011-04-03 04:49 -0500

#2121 — Searching a CSV file - beginner seeking help

Hi all. I've written a little script to search a csv file for films. It
works but has problems. I'd appreciate any pointers with the following:

1. I've used instance variables without a class, to make them visible
amongst methods. Is this acceptable for a short script like this?

2. As it is, it will only match exactly. For example, I have The Mummy
and The Mummy Returns. If I search for 'mummy' program reports "film not
found." I know I need to use Regexp's, not sure how to implement it here
though.

3. Any other comments gratefully received.


#################
# search_films.rb
#################

require 'csv'

def load_xvid_file(path_to_csv)
  @names = []
  csv_contents = CSV.read(path_to_csv)
  csv_contents.shift
  csv_contents.each do |row|
    @names << row[0]
  end
  @names.each { |f| f.downcase! }
end

def search_for_film
  print "Enter name of film to search for: "
  film = gets.chomp.downcase
  puts

  if @names.include?(film)
    puts "#{film} found!"
  else
    puts "#{film} not found :("
  end
  prompt
end

def prompt
  print "Search again? (y or n) "
  answer = gets.chomp.downcase

  case answer
  when /y/
    search_for_film
  when /n/
    puts "Goodbye."
    exit
  else
    prompt
  end
end

load_xvid_file("/home/simon/Documents/CSV/XviD.csv")
search_for_film

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#2128

Got it!

def search_for_film
  print "Enter name of film to search for: "
  film = gets.chomp.downcase

  results = @films.grep(/#{film}/)
  if results
    puts results
    menu
  elsif results.empty?
    puts "Nothing found."
    menu
  else
    menu
  end
end

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#2132

This works perfectly for me now. In case anyone may benefit from it:


require 'csv'

def load_xvid_file(path_to_csv)
  @films = []
  csv_contents = CSV.read(path_to_csv)
  csv_contents.shift
  csv_contents.each do |row|
    @films << row[0]
  end
  @films.each { |f| f.downcase! }
end

def search_for_film
  print "Enter name of film to search for: "
  film = gets.chomp.downcase

  results = [@films.grep(/#{film}/)]
  if results
    results.each { |f| puts f }
    prompt
  else
    puts "Nothing found."
    prompt
  end
end

def prompt
  print "Search again? (y or n) "
  answer = gets.chomp.downcase

  case answer
  when /^y/
    search_for_film
  when /^n/
    puts "Goodbye."
    exit
  else
    prompt
  end
end

load_xvid_file("/home/simon/Documents/CSV/XviD.csv")
search_for_film

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#2134

On Fri, Apr 1, 2011 at 11:26 PM, Simon Harrison <simon@simonharrison.net> wrote:
> This works perfectly for me now. In case anyone may benefit from it:
>
>
> require 'csv'
>
> def load_xvid_file(path_to_csv)
>  @films = []
>  csv_contents = CSV.read(path_to_csv)
>  csv_contents.shift
>  csv_contents.each do |row|
>    @films << row[0]
>  end
>  @films.each { |f| f.downcase! }
> end
>
> def search_for_film
>  print "Enter name of film to search for: "
>  film = gets.chomp.downcase
>
>  results = [@films.grep(/#{film}/)]
>  if results

this will always be true, since you are initializing results to an
array. Enumerable#grep already returns an array, so I'd do:

results = @films.grep(/#{film}/)
if results.empty?
  puts "nothing found"
else
  results.each ...


if results
>    results.each { |f| puts f }
>    prompt
>  else
>    puts "Nothing found."
>    prompt
>  end
> end
>
> def prompt
>  print "Search again? (y or n) "
>  answer = gets.chomp.downcase
>
>  case answer
>  when /^y/
>    search_for_film
>  when /^n/
>    puts "Goodbye."
>    exit
>  else
>    prompt
>  end
> end
>
> load_xvid_file("/home/simon/Documents/CSV/XviD.csv")
> search_for_film

By the way, I'd change a bit around the logic and the user interface,
you seem to have both a little bit mixed up. I would call method
prompt from the main script, in that method I would ask the user for a
word and call search_for_film passing what the user typed. From that
method I would return the results array. Back in the prompt method, I
would print the results and loop for another run. This way,
search_for_film is not tied to the specific user interaction and is
more general and easier to refactor and reuse.

Jesus.

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#2133

Sorry, don't know your name. You're just appearing as 'guest'. Are you 
sure it's a good idea to have globals in block variables? I've been 
continuing to play and the following seems to be what I'm after. Sadly 
nothing prints out and the program exits.


def search_for_film
  print "Enter name of film to search for: "
  film = gets.chomp.downcase

  results = @films.grep(/film/)
  if results
    print results
  elsif results.empty?
    puts "Nothing found."
  else
    menu
  end
end


Here is irb demonstrating that it *should* work!


irb(main):009:0> films = ['the mummy', 'the mummy returns', 'the mummy 
7', 'the daddy']
=> ["the mummy", "the mummy returns", "the mummy 7", "the daddy"]
irb(main):010:0> films.grep(/mummy/)
=> ["the mummy", "the mummy returns", "the mummy 7"]
irb(main):011:0>

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#2149

Thanks Jesus. I plan to improve script over coming days.

-- 
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#2152

On Apr 2, 4:39 am, Simon Harrison <si...@simonharrison.net> wrote:
> Thanks Jesus. I plan to improve script over coming days.
>
> --
> Posted viahttp://www.ruby-forum.com/.

Hi Simon, just a tip, there is a ruby library to deal with CSV data in
a way very similar to ActiveRecord, but just doesn't work with ruby
1.9.
https://github.com/marcofognog/active_csv

Regards

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#2187

Thanks marco. Looks like it has potential. I can't think how it would 
really help me with this little project but thanks for the link.

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