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Contents
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied. See the License for the
# specific language governing permissions and limitations
# under the License.
module Arrow
# Experimental
#
# TODO: Almost codes should be implemented in Apache Arrow C++.
class RollingWindow
def initialize(table, size)
@table = table
@size = size
end
def lag(key, diff: 1)
column = @table[key]
if @size
windows = column.each_slice(@size)
else
windows = column
end
lag_values = [nil] * diff
windows.each_cons(diff + 1) do |values|
target = values[0]
current = values[1]
if target.nil? or current.nil?
lag_values << nil
else
lag_values << current - target
end
end
ArrayBuilder.build(lag_values)
end
end
end
Version data entries
40 entries across 40 versions & 1 rubygems