plot.rb

require 'csv'
require 'numo/gnuplot' # You must run `gem install numo-gnuplot`

KEYWORD = 'にのめ'

tweets_file_path = ARGV[0] || 'tweets.csv'
csv = CSV.open(tweets_file_path, headers: true)

# Convert from CSV to array of Hash.
tweets = csv.map {|row| row.to_hash }
# Exclude retweets.
tweets = tweets.select {|t| t['retweeted_status_id'].empty? }
# Convert timestamp to Time object.
tweets.each {|t| t['timestamp'] = DateTime.parse(t['timestamp']).to_time }

# Select tweets tweeted in this year.
this_year_tweets = tweets.select {|t| t['timestamp'] >= Time.new(2016, 1, 1, 0, 0, 0) }
# Group tweets by same date.
this_year_tweets_by_date = this_year_tweets.group_by {|t| t['timestamp'].to_date }

# Count tweets
all_tweet_counts = this_year_tweets_by_date.map {|date, ts| [date, ts.size] }.to_h
ninome_tweet_counts = this_year_tweets_by_date.map {|date, ts| [date, ts.count {|t| t['text'].include?(KEYWORD) }] }.to_h

puts "All tweets: ##{all_tweet_counts.values.reduce(:+)}"
puts "Tweets including \"#{KEYWORD}\": ##{ninome_tweet_counts.values.reduce(:+)}"

x = ninome_tweet_counts.keys.map {|date| date.to_s }
y = ninome_tweet_counts.values

Numo.gnuplot do
  set 'datafile separator " "'

  set 'xdata time'
  set 'timefmt "%Y-%m-%d"'

  set 'xrange ["2016-01-01":"2016-12-31"]'
  set "yrange [0:#{y.max + 1}]"
  set 'format x "%m/%d"'
  unset 'key'

  unless ENV['DEBUG']
    set 'terminal png size 1280,320'
    set 'output "tweet_counts.png"'
  end

  plot x, y, using: '1:2', with: 'impulses', lw: 2

  gets if ENV['DEBUG']
end