连接所有值并将它们附加到同一变量
连接所有值并将它们附加到同一变量
提问于 2013-01-18 00:35:12
我尝试将所有值连接起来，并将它们附加到同一个变量中，然后编写字符串的内容。我一直收到这样的错误：“尝试连接全局'arglist‘(一个nil值)”
eo_device = {}
eo_device[1] = {node = "ME", t_object = "AV1", h_object = "AV2" }
eo_device[2] = {node = "ME", t_object = "AV3", h_object = "AV4" }
eo_device[3] = {node = "ME", t_object = "AV5", h_object = "AV6" }
eo_device[4] = {node = "ME", t_object = "AV7", h_object = "AV8" }
eo_device[5] = {node = "ME", t_object = "AV9", h_object = "AV10" }
eo_device[6] = {node = "ME", t_object = "AV11", h_object = "AV12" }
eo_device[7] = {node = "ME", t_object = "AV13", h_object = "AV14" }
eo_device[8] = {node = "ME", t_object = "AV15", h_object = "AV16" }
eo_device[9] = {node = "ME", t_object = "AV17", h_object = "AV18" }
eo_device[10] = {node = "ME", t_object = "AV19", h_object = "AV20" }
eo_device[11] = {node = "ME", t_object = "AV21", h_object = "AV22" }
eo_device[12] = {node = "ME", t_object = "AV23", h_object = "AV24" }
eo_device[13] = {node = "ME", t_object = "AV25", h_object = "AV26" }
eo_device[14] = {node = "ME", t_object = "AV27", h_object = "AV28" }
eo_device[15] = {node = "ME", t_object = "AV29", h_object = "AV30" }
-- Generate string with all arguments to be written to CSV
for deviceindex = 1,#eo_device do
device_name = scl.nodes[eo_device[deviceindex].node][eo_device[deviceindex].t_object .. "_Object_Name"].value -- point to Object Names
description = scl.nodes[eo_device[deviceindex].node][eo_device[deviceindex].t_object .. "_Description"].value -- point to Description of all objects
temperature = scl.nodes[eo_device[deviceindex].node][eo_device[deviceindex].t_object .. "_Present_Value"].value -- value of temperature object
humidity = scl.nodes[eo_device[deviceindex].node][eo_device[deviceindex].h_object .. "_Present_Value"].value -- value of humidity object
buflist = device_name .. "," .. description .. "," .. temperature .. "," .. humidity
arglist = arglist .. "," .. buflist
end -- end for
--then once outside of the loop:
arglist = arglist .. "," .. buflist
buffer = os.date() .. arglist .. "\r\n"
file, info = io.open("trend.csv", "a+") -- write to CSV
if file then
file:write(buffer)
file:close()
end -- end if回答 1
Stack Overflow用户
回答已采纳
发布于 2013-01-18 01:14:23
我一直收到这样的错误：“尝试连接全局'arglist‘(一个nil值)”
因为您正尝试在代码的第31行连接arglist ( nil值)：
arglist = arglist .. "," .. buflist arglist永远不会初始化，所以当您尝试在=的右侧进行连接时，您会得到该错误。
关于此循环的附注：
for deviceindex = 1,#eo_device do
description = scl.nodes[eo_device[deviceindex].node][eo_device[deviceindex].t_object .. "_Description"].valueLua有一个“通用的”for循环，它允许你遍历eo_device的所有元素，给你索引和值，所以你不需要在循环中建立索引。这会让你的代码更整洁一些：
for deviceindex, device in ipairs(eo_device) do
description = scl.nodes[device.node][device.t_object .. "_Description"].value关于此代码的附注：
buflist = device_name .. "," .. description .. "," .. temperature .. "," .. humidity 构建这样的字符串是非常低效的。在循环中执行此操作将导致数千个字符串连接，并生成大量垃圾。一种更好的方法是将所有字符串部分添加到一个表中，然后通过table.concat将它们连接成一个逗号分隔的字符串。
例如，要创建一个包含eo_device表中所有字符串的逗号分隔字符串：
local buffer = {}
for i,device in ipairs(eo_device) do
table.insert(buffer, device.node)
table.insert(buffer, device.t_object)
table.insert(buffer, device.h_object)
end
devices = table.concat(buffer, ',')页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/14383728
复制相关文章
相似问题
腾讯云开发者
