tiree-data.rb

# USAGE (in ruby interpreter)
# 
# require './tiree-data.rb'
# wind_speed = 5.0 #in m/s
# result = estimate(wind_speed)

#For estimating E-44 output
def estimate(windspeed)
  #some rounding to make sure ranges are intact
  windspeed = windspeed.round(3)

  #lookup format => [windspeed (ms), output (kw), coefficient]
  lookup = [[1, 0, 0.0], [2, 0, 0.0], [3, 4, 0.16], [4, 20, 0.34], [5, 50, 0.43], [6, 96, 0.48], 
    [7, 156, 0.49], [8, 238, 0.5], [9, 340, 0.5], [10, 466, 0.5], [11, 600, 0.48], [12, 710, 0.44], 
    [13, 790, 0.39], [14, 850, 0.33], [15, 880, 0.28], [16, 905, 0.24], [17, 910, 0.2], [18, 910, 0.17], 
    [19, 910, 0.14], [20, 910, 0.12], [21, 910, 0.11], [22, 910, 0.09], [23, 910, 0.08], [24, 910, 0.07], [25, 910, 0.06]] 
  #turn windspeeds into ranges for lookup 
  ranges = []
  min = 0.0
  max = 1.999
  lookup.each_with_index do |row, index|
    min = row[0] unless index.eql?(0)
    max = row[0] + 0.999 #speed
    ranges << [(min..max), row[1].to_f]
  end
  
  #find windspeed value
  output = 0.0
  return output if windspeed > 25.0 #cut off point
  ranges.each_with_index do |power_range, index|
    if power_range[0].include? windspeed
      output = power_range[1] # find power from lookup
      decimals = windspeed - windspeed.floor # take account of decimal places
      break if decimals.eql?(0.0) or output.eql?(910) or output.eql?(0.0) #no need to fill in the blanks
      next_output = ranges[index+1][1] 
      output = ((next_output - output) * decimals) + output
      break
    end
  end
  return output
end


#For converting wunderground json to csv
def observations
  f= File.read("weather.json")
  j = JSON.parse f
  data = []
  j["history"]["observations"].each do |obsv| 
    #2013-11-01 00:00:00
    yr = obsv['date']['year']
    mm = obsv['date']['mon']
    dd = obsv['date']['mday']
    hr = obsv['date']['hour']
    min = obsv['date']['min']
    time = "#{yr}-#{mm}-#{dd} #{hr}:#{min}:00"
    windspeed = obsv["wspdm"].to_f*1000/3600
    data << [time, estimate(windspeed), windspeed]
  end
  
  CSV.open("nov-weather.csv", "wb") do |csv|
    csv << ["timestamp", "estimate", "windspeed"]
    for row in data
      csv << row
    end
  end
end

#For converting SCADA format
def tiree_csv(filepath)
  data = CSV.read(filepath)
  #EACH ROW IS A DAY
  days = []
  for row in data
    day = []
    next if row.eql? data[0] # skip heading
    tp_count = 0
    data[0].each_with_index do |heading, i| 
      if heading[0..1].eql? "TP" #add value to day if TP column 
        timestamp  = Time.strptime row[4], "%d-%b-%y"
        timestamp = timestamp + (tp_count * 30.minutes) 
        tp_count += 1
        day << [timestamp, row[i]] 
      end
    end
    days << day
  end

  CSV.open("tiree-redone.csv", "wb") do |csv|
    csv << ["Timestamp", "Output"]
    for day in days.flatten(1)
      csv << day
    end
  end
end