Class: Xgb::Booster

Inherits:
Object
  • Object
show all
Includes:
Utils
Defined in:
lib/xgb/booster.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(params: nil, model_file: nil) ⇒ Booster

Returns a new instance of Booster.



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# File 'lib/xgb/booster.rb', line 5

def initialize(params: nil, model_file: nil)
  @handle = ::FFI::MemoryPointer.new(:pointer)
  check_result FFI.XGBoosterCreate(nil, 0, @handle)
  if model_file
    check_result FFI.XGBoosterLoadModel(handle_pointer, model_file)
  end

  self.best_iteration = 0
  set_param(params)
end

Instance Attribute Details

#best_iteration ⇒ Object

Returns the value of attribute best_iteration.



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# File 'lib/xgb/booster.rb', line 3

def best_iteration
  @best_iteration
end

#feature_names ⇒ Object

Returns the value of attribute feature_names.



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# File 'lib/xgb/booster.rb', line 3

def feature_names
  @feature_names
end

Instance Method Details

#dump(fmap: "", with_stats: false, dump_format: "text") ⇒ Object

returns an array of strings



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# File 'lib/xgb/booster.rb', line 60

def dump(fmap: "", with_stats: false, dump_format: "text")
  out_len = ::FFI::MemoryPointer.new(:ulong)
  out_result = ::FFI::MemoryPointer.new(:pointer)
  check_result FFI.XGBoosterDumpModelEx(handle_pointer, fmap, with_stats ? 1 : 0, dump_format, out_len, out_result)
  out_result.read_pointer.get_array_of_string(0, out_len.read_ulong)
end

#dump_model(fout, fmap: "", with_stats: false, dump_format: "text") ⇒ Object 



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# File 'lib/xgb/booster.rb', line 67

def dump_model(fout, fmap: "", with_stats: false, dump_format: "text")
  ret = dump(fmap: fmap, with_stats: with_stats, dump_format: dump_format)
  File.open(fout, "wb") do |f|
    if dump_format == "json"
      f.print("[\n")
      ret.each_with_index do |r, i|
        f.print(r)
        f.print(",\n") if i < ret.size - 1
      end
      f.print("\n]")
    else
      ret.each_with_index do |r, i|
        f.print("booster[#{i}]:\n")
        f.print(r)
      end
    end
  end
end

#eval_set(evals, iteration) ⇒ Object 



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# File 'lib/xgb/booster.rb', line 20

def eval_set(evals, iteration)
  dmats = ::FFI::MemoryPointer.new(:pointer, evals.size)
  dmats.write_array_of_pointer(evals.map { |v| v[0].handle_pointer })

  evnames = ::FFI::MemoryPointer.new(:pointer, evals.size)
  evnames.write_array_of_pointer(evals.map { |v| ::FFI::MemoryPointer.from_string(v[1]) })

  out_result = ::FFI::MemoryPointer.new(:pointer)

  check_result FFI.XGBoosterEvalOneIter(handle_pointer, iteration, dmats, evnames, evals.size, out_result)

  out_result.read_pointer.read_string
end

#fscore(fmap: "") ⇒ Object 



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# File 'lib/xgb/booster.rb', line 86

def fscore(fmap: "")
  # always weight
  score(fmap: fmap, importance_type: "weight")
end

#predict(data, ntree_limit: nil) ⇒ Object 



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# File 'lib/xgb/booster.rb', line 44

def predict(data, ntree_limit: nil)
  ntree_limit ||= 0
  out_len = ::FFI::MemoryPointer.new(:ulong)
  out_result = ::FFI::MemoryPointer.new(:pointer)
  check_result FFI.XGBoosterPredict(handle_pointer, data.handle_pointer, 0, ntree_limit, out_len, out_result)
  out = out_result.read_pointer.read_array_of_float(out_len.read_ulong)
  num_class = out.size / data.num_row
  out = out.each_slice(num_class).to_a if num_class > 1
  out
end

#save_model(fname) ⇒ Object 



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# File 'lib/xgb/booster.rb', line 55

def save_model(fname)
  check_result FFI.XGBoosterSaveModel(handle_pointer, fname)
end

#score(fmap: "", importance_type: "weight") ⇒ Object 



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# File 'lib/xgb/booster.rb', line 91

def score(fmap: "", importance_type: "weight")
  if importance_type == "weight"
    trees = dump(fmap: fmap, with_stats: false)
    fmap = {}
    trees.each do |tree|
      tree.split("\n").each do |line|
        arr = line.split("[")
        next if arr.size == 1

        fid = arr[1].split("]")[0].split("<")[0]
        fmap[fid] ||= 0
        fmap[fid] += 1
      end
    end
    fmap
  else
    average_over_splits = true
    if importance_type == "total_gain"
      importance_type = "gain"
      average_over_splits = false
    elsif importance_type == "total_cover"
      importance_type = "cover"
      average_over_splits = false
    end

    trees = dump(fmap: fmap, with_stats: true)

    importance_type += "="
    fmap = {}
    gmap = {}
    trees.each do |tree|
      tree.split("\n").each do |line|
        arr = line.split("[")
        next if arr.size == 1

        fid = arr[1].split("]")

        g = fid[1].split(importance_type)[1].split(",")[0].to_f

        fid = fid[0].split("<")[0]

        fmap[fid] ||= 0
        gmap[fid] ||= 0

        fmap[fid] += 1
        gmap[fid] += g
      end
    end

    if average_over_splits
      gmap.each_key do |fid|
        gmap[fid] = gmap[fid] / fmap[fid]
      end
    end

    gmap
  end
end

#set_param(params, value = nil) ⇒ Object 



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# File 'lib/xgb/booster.rb', line 34

def set_param(params, value = nil)
  if params.is_a?(Enumerable)
    params.each do |k, v|
      check_result FFI.XGBoosterSetParam(handle_pointer, k.to_s, v.to_s)
    end
  else
    check_result FFI.XGBoosterSetParam(handle_pointer, params.to_s, value.to_s)
  end
end

#update(dtrain, iteration) ⇒ Object 



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# File 'lib/xgb/booster.rb', line 16

def update(dtrain, iteration)
  check_result FFI.XGBoosterUpdateOneIter(handle_pointer, iteration, dtrain.handle_pointer)
end