8.方差、标准差、离散率

例1

--==========================配置项==========================
--要参与运算的设备名称数组
local dev_name_arr={"device1","device2"}
--参与运算的数据的物模型标识
local tag_model_arr={"Ipv1","Ipv2","Ipv3","Ipv4","Ipv5","Ipv6","Ipv7","Ipv8"}
--==========================配置项==========================

--==========================函数==========================
--平均值
function calculate_average(data)
    local sum = 0
    local count = 0

    for _, value in ipairs(data) do
        sum = sum + value
        count = count + 1
    end

    if count > 0 then
        return sum / count
    else
        return 0
    end
end
--方差
function calculate_variance(data)
    local n = #data
    if n <= 1 then
        return 0
    end

    local mean = calculate_average(data)

    local sum_squared_diff = 0
    for _, value in ipairs(data) do
        sum_squared_diff = sum_squared_diff + (value - mean)^2
    end
    return sum_squared_diff / n
end
--标准差
function calculate_standard_deviation(data)
    local variance = calculate_variance(data)
    local standard_deviation = math.sqrt(variance)
    return standard_deviation
end
--==========================函数==========================





local avg_result = {}--平均值
local var_result = {}--方差
local sd_result = {}--标准差
local coe_result = {}--离散率

for dev_idx = 1,#dev_name_arr do
  local tag_value_arr = {}
  for tag_idx = 1,#tag_model_arr do
    tag_value_arr[tag_idx] = GetDevTagValue(dev_name_arr[dev_idx],tag_model_arr[tag_idx])
  end
  avg_result[dev_idx] = calculate_average(tag_value_arr)
  var_result[dev_idx] = calculate_variance(tag_value_arr)
  sd_result[dev_idx] = calculate_standard_deviation(tag_value_arr)
  coe_result[dev_idx] = sd_result[dev_idx] / avg_result[dev_idx]
end


for dev_idx = 1,#dev_name_arr do
    --LuaClog("平均值",avg_result[dev_idx])
    --LuaClog("方差",var_result[dev_idx])
    --LuaClog("标准差",sd_result[dev_idx])
    --LuaClog("离散率",coe_result[dev_idx])
    SetDevTagValue(dev_name_arr[dev_idx],"result",coe_result[dev_idx])
end

• 说明：

  有两个逆变器分别为device1和device2，要分别计算各自支路电流（其测点物模型标识分别为Ipv1、Ipv2...）的离散率，先调用calculate_average函数计算平均值，再调用calculate_standard_deviation函数计算标准差，然后将标准差除以平均值来计算离散率，最后将离散率写入到各自设备下物模型标识为result的计算点中。

• 附：

  上述脚本中用到的自定义函数。

  --平均值
  function calculate_average(data)
      local sum = 0
      local count = 0
  
      for _, value in ipairs(data) do
          sum = sum + value
          count = count + 1
      end
  
      if count > 0 then
          return sum / count
      else
          return 0
      end
  end
  --方差
  function calculate_variance(data)
      local n = #data
      if n <= 1 then
          return 0
      end
  
      local mean = calculate_average(data)
  
      local sum_squared_diff = 0
      for _, value in ipairs(data) do
          sum_squared_diff = sum_squared_diff + (value - mean)^2
      end
      return sum_squared_diff / n
  end
  --标准差
  function calculate_standard_deviation(data)
      local variance = calculate_variance(data)
      local standard_deviation = math.sqrt(variance)
      return standard_deviation
  end