Simple Lua Object that can read and modify a CSV file. Strings containing a comma (,) are not supported.

Simple-CSV.lua

--Initialise
SimpleCSV = {}
SimpleCSV.__index = SimpleCSV

--Create new object
function SimpleCSV.new()
  self = setmetatable({},SimpleCSV)
	self.csv_table = {}
	return self
end

--[[
Load CSV File into multidimensional table.
parmeter: filepath is the location of the csv file
returns: True is file exists and has been loaded
]]
function SimpleCSV:load_csvfile(filepath)
	local file = io.open(filepath,"r")
	if file then
		for line in file:lines() do
			local temp = {}
			for item in string.gmatch(line,"[^,]*") do --does not work for strings containing ','
				if item ~= "" then
					item = item:gsub(",","")
					item = item:gsub("^%s*(.-)%s*$", "%1") -- remove trailing white spaces
					table.insert(temp,item)
				end
			end
			table.insert(self.csv_table, temp)
		end
	else
		print("Cannot open file: "..filepath)
		return false
	end
	return true
end

--[[
Display csv file loaded into table
returns: None
]]
function SimpleCSV:display_csvfile()
	if next(self.csv_table) ~= nil then
		for rowCount = 1, #self.csv_table do
			print(unpack(self.csv_table[rowCount]))
		end
	else
		print("No CSV Table found!!")
	end
end

--[[
Write to a CSV File from the multidimensional table.
parmeter: filepath is the location of the csv file
returns: None
]]
function SimpleCSV:write_csvfile(filepath)
	local outfile = io.open(filepath,"w")
	if outfile then
		if next(self.csv_table) ~= nil then
			for rowCount = 1, #self.csv_table do
				row = self.csv_table[rowCount]
				for i,item in pairs(row) do
					if i ~= #row then
						outfile:write(item..",")
					else
						outfile:write(item.."\n")
					end
				end
			end
		else
			print("No CSV Table found!!")
		end
	else
		print("Cannot write to file: "..filepath)
	end
end

--[[
Displays the attribute in a particular row and column of the table
parameter: row is the row number in the table
parameter: column is the column number in the table
returns: string value of the attribute
]]
function SimpleCSV:get_attribute(row, column)
	if next(self.csv_table) ~= nil then
		if row > #self.csv_table or row < 0 then
			print("Row is outside of allowed range")
		else
			row_attr = self.csv_table[row]
			if column > #row_attr or column < 0 then
				print("Column is outside of allowed range")
			else
				return row_attr[column]
			end
		end
	else
		print("No CSV Table found!!")
	end
	return "No Attribute found"
end

--[[
Changes a specific attribute in table to a given value
parameter: row is the row number in the table
parameter: column is the column number in the table
parameter: value is the attribute to be set
returns: True if value was sucessfully changed
]]
function SimpleCSV:set_attribute(row,column,value)
	if next(self.csv_table) ~= nil then
		if row > #self.csv_table or row < 0 then
			print("Row is outside of allowed range")
		else
			row_attr = self.csv_table[row]
			if column > #row_attr or column < 0 then
				print("Column is outside of allowed range")
			else
				row_attr[column] = value
				return true
			end
		end
	else
		print("No CSV Table found!!")
	end
	return false
end

--[[
Searches the table and gives the location of the first instance of a user-defined attribute
parameter: attr is the attribute given by the user
returns: the row and column of the defined attribute if found
]]
function SimpleCSV:find_attribute(attr)
	if next(self.csv_table) ~= nil then
		local rowIndex = 1
		repeat
			local columns = self.csv_table[rowIndex]
			for columnIndex,item in pairs(columns) do
				if string.lower(attr) == string.lower(item) then
					return "Attribute \""..attr.."\" found in row "..rowIndex..", column "..columnIndex
				end
			end
			rowIndex = rowIndex + 1
		until rowIndex > #self.csv_table
		return "Attribute: \""..attr.."\" not found"
	else
		print("No CSV Table found!!")
	end
end

--[[
Searches the table and gives the row and column indexes of the first instance of a user-defined attribute
parameter: attr is the attribute given by the user
returns: the row and column indexes as a table
]]
function SimpleCSV:get_location(attr)
	if next(self.csv_table) ~= nil then
		local rowIndex = 1
		repeat
			local columns = self.csv_table[rowIndex]
			for columnIndex,item in pairs(columns) do
				if string.lower(attr) == string.lower(item) then
					return {["row"]=rowIndex,["col"]=columnIndex}
				end
			end
			rowIndex = rowIndex + 1
		until rowIndex > #self.csv_table
		return {["row"]=0,["col"]=0}
	else
		print("No CSV Table found!!")
	end
end

--[[
Searches the table and gives the row and column indexes of all instances of a user-defined attribute
parameter: attr is the attribute given by the user
returns: the row and column indexes as a multidimensional table
]]
function SimpleCSV:get_locations(attr)
	if next(self.csv_table) ~= nil then
		local rowIndex = 1
		local pos = {}
		repeat
			local columns = self.csv_table[rowIndex]
			for columnIndex,item in pairs(columns) do
				if string.lower(attr) == string.lower(item) then
					table.insert(pos,{["row"]=rowIndex,["col"]=columnIndex})
				end
			end
			rowIndex = rowIndex + 1
		until rowIndex > #self.csv_table
		return pos
	else
		print("No CSV Table found!!")
	end
end

--[[
Adds a row to the end of the table
parameter: elements is the row to be added.
returns: true if row was sucessfully added to table
]]
function SimpleCSV:add_row(elements)
	if next(self.csv_table) ~= nil then
		local firstRow = self.csv_table[1]
		if #elements == #firstRow then
			table.insert(self.csv_table,elements)
			return true
		else
			print("Number of columns do not match")
		end
	else
		print("No CSV Table found!!")
	end
	return false
end

--[[
**********Test section**********

CSV file: test.csv

1, Tom, 34, Man, Electrician
2, Dan, 34, Man, Business Man
3, Stan, 34, Man, Programmer
4, Douglas, 34, Man, Shop Owner
5, Sarah, 34, Woman, Beautician
6, Joan, 34, Woman, Business Woman
7, Jenny, 34, Woman, Fashion Designer
8, Suzie, 34, Woman, Engineer

]]

--Start
csv = SimpleCSV.new() --Create object
csv:load_csvfile("test.csv") --Load File (true)
csv:display_csvfile()
--[[

Output:

1	Tom	34	Man	Electrician
2	Dan	34	Man	Business Man
3	Stan	34	Man	Programmer
4	Douglas	34	Man	Shop Owner
5	Sarah	34	Woman	Beautician
6	Joan	34	Woman	Business Woman
7	Jenny	34	Woman	Fashion Designer
8	Suzie	34	Woman	Engineer

]]

print(csv:get_attribute(1,2)) --Tom

print(csv:get_attribute(2,2)) --Dan
csv:set_attribute(2,2,"John")
print(csv:get_attribute(2,2)) --John

print(csv:find_attribute("Man")) --Attribute "Man" found in row 1, column 4

loc1 = csv:get_location("Man")
print("row = "..loc1.row.." , col = "..loc1.col) --row = 1 , col = 4

loc2 = csv:get_locations("Man")
for i,v in pairs(loc2) do
	print("row => "..v.row.." , col => "..v.col)
end
--[[

Output:

row => 1 , col => 4
row => 1 , col => 4
row => 2 , col => 4
row => 3 , col => 4
row => 4 , col => 4

]]

newrow = {9,"Carol",44,"Woman","IT Professional"}
csv:add_row(newrow)
csv:display_csvfile()

--[[

Output:

1	Tom	34	Man	Electrician
2	John	34	Man	Business Man
3	Stan	34	Man	Programmer
4	Douglas	34	Man	Shop Owner
5	Sarah	34	Woman	Beautician
6	Joan	34	Woman	Business Woman
7	Jenny	34	Woman	Fashion Designer
8	Suzie	34	Woman	Engineer
9	Carol	44	Woman	IT Professional

]]