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@bradland
Last active Aug 29, 2015
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Boilerplate CSV analysis script
#!/usr/bin/env ruby
require 'csv'
require 'ostruct'
require 'optparse'
require 'i18n'
require 'set' # this should only be required until i18n updates to new rev
require 'active_support/core_ext/string/inflections'
I18n.enforce_available_locales = true # I18n spams warn unless this is set
class CSVAnalyze
::Version = [0,0,1]
attr_accessor :options
# $stdout.sync = true # prevents buffering of output; uncomment this only if you need it.
Signal.trap(:INT, :EXIT) # Trap ctrl+c from users or `kill -SIGINT pid` from shell and exits from pipe chains
def initialize(args, options = {})
# Handle options
@options = OpenStruct.new
@options.format = :tsv
opt_parser = OptionParser.new do |opt|
opt.banner = "Usage: #{$0} [OPTION]... [FILE]..."
opt.on("-c","--csv","Output CSV format instead of standard TSV") do
@options.format = :csv
end
opt.on_tail("-h","--help","Print usage information.") do
$stderr.puts opt_parser
exit 1
end
opt.on_tail("--version", "Show version") do
puts ::Version.join('.')
exit 1
end
end
begin
opt_parser.parse!
rescue OptionParser::InvalidOption => e
$stderr.puts "Specified #{e}"
$stderr.puts opt_parser
exit 64 # EX_USAGE
end
end
def run!
@data = ARGF.readlines # slurps entire file (refactor to block form if working with large files!)
# BEGIN data pre-processing
# Extract headers from first line
headers = CSV.parse(data.shift).first.map { |col| col.parameterize.underscore.to_sym }
# Parse CSV and convert to hash rows
data.map! { |line| line.parse_csv }
data.map! { |row| Hash[headers.zip(row)] }
# END data pre-processing
# BEGIN data analysis
summaries = data.each.with_index.collect do |row, i|
# This is where you do the work.
row[:some_column] = "Some computed value goes here."
row
end
# END data analysis
# BEGIN report to stdout
case @options.format
when :tsv
puts summaries.first.keys.join("\t")
summaries.each do |row|
puts row.values.join("\t")
end
when :csv
puts summaries.first.keys.to_csv
summaries.each do |row|
puts row.values.to_csv
end
end
# END report to stdout
end
end
begin
if $0 == __FILE__
CSVAnalyze.new(ARGV).run!
end
rescue Interrupt
# Ctrl^C
exit 130
rescue Errno::EPIPE
# STDOUT was closed
exit 74 # EX_IOERR
end
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