pretty print to a file in ruby

问题

I am trying to pretty print a hash to a file.

I tried unix redirects [added different flags to it incrementally] :

`echo #{pp  mymap} | tee summary.out 2>&1`

and File IO

 my_file = File.new(@dir_+"/myfile.out",'w+')          
 my_file.puts `#{pp get_submap_from_final(all_mapping_file,final_map)}`

It always prints to console and doesnt write to a file.

Also there has to be an easier way to write to file in one line in ruby ? instead of doing File.new and then writing to a file ?

回答1:

require 'pp'

File.open("test.txt","w") do |f|
  PP.pp(self,f)
end

回答2:

The use of backticks here is perplexing since those are used for executing shell commands.

What you probably mean is:

File.open(@dir_+"/myfile.out",'w+') do |f|
  f.write(pp(get_submap_from_final(all_mapping_file,final_map)))
end

The pp method always writes to the console so you might see it and still have it written.

回答3:

What about (not using pp directly):

File.open("myfile.out","w+") do |f|
  f.puts mymap.inspect
end

Or even redirect stdout for the file

file = File.open("myfile.out", "w+)

old_stdout = STDOUT

$stdout = STDOUT = file

pp get_submap_from_final(all_mapping_file,final_map)

$stdout = STDOUT = old_stdout

回答4:

Doing something similar to what Edu suggested and How do I redirect stderr and stdout to file for a Ruby script? helped.

Here is how the new code is similar to:

$stdout.reopen(@dir_+"/my_file.out",'w+')
puts "All metrics are:"
pp final_map
$stdout=STDOUT

Would still be interested to know why redirection operators > , and 2>&1 in back-ticks doesn't work

回答5:

Given the mymap from the question, you can use the "show_data" gem, which provides two methods: show_data and format_data. The latter produces a "pretty-printed" string of its argument which can then be fed to any output method.

require 'show_data'

$stderr.puts format_data(mymap)

For example:

myhash = { 'owners' => 21050, 'users' => 16877, 'portfolios' => 583, 
           'properylists' => 0, 'properties' => 29504, 'units' => 62688, 
           'tenants' => 85856 }
$stderr.puts format_data(myhash)

on STDERR:

 {      'owners' => 21050,
         'users' => 16877,
    'portfolios' => 583,
  'properylists' => 0,
    'properties' => 29504,
         'units' => 62688,
       'tenants' => 85856
}

回答6:

require 'pp'

class File
  def pp(*objs)
    objs.each {|obj|
      PP.pp(obj, self)
    }
    objs.size <= 1 ? objs.first : objs
  end
end

File.open('output','w') do |file|
  file.pp mymap
end

回答7:

Here's an expansion to the post above to also to pretty print json output to a file.

require "pp"
require "json"

class File
  def pp(*objs)
    objs.each {|obj|
      PP.pp(obj, self)
    }
    objs.size <= 1 ? objs.first : objs
  end
  def jj(*objs)
    objs.each {|obj|
      obj = JSON.parse(obj.to_json)
      self.puts JSON.pretty_generate(obj)
    }
    objs.size <= 1 ? objs.first : objs
  end
end

test_object = { :name => { first: "Christopher", last: "Mullins" }, :grades => [ "English" => "B+", "Algebra" => "A+" ] }

test_json_object = JSON.parse(test_object.to_json)

File.open("log/object_dump.txt", "w") do |file|
  file.pp(test_object)
end

File.open("log/json_dump.txt", "w") do |file|
  file.jj(test_json_object)
end

来源：https://stackoverflow.com/questions/9234899/pretty-print-to-a-file-in-ruby

标签

ruby

file-io

pretty-print