Data update

Task/CSV-data-manipulation/Lua/csv-data-manipulation-1.lua

@@ -0,0 +1,13 @@
+-- Lua has no built in methods to handle csv files.
+-- it does have string.gmatch, which we use to global.match whatever isn't a comma
+
+print(io.read"l" .. ",SUM")
+for line in io.lines() do
+	local fields, sum = {}, 0
+	for field in line:gmatch"[^,]+" do
+		table.insert(fields, field)
+		sum = sum + field
+	end
+	table.insert(fields, sum)
+	print(table.concat(fields,","))
+end

Task/CSV-data-manipulation/Lua/csv-data-manipulation-2.lua

@@ -0,0 +1,26 @@
+local csv={}
+
+-- read csv file, save records and fields into table
+for line in io.lines('file.csv') do
+    local fields = {}
+    for field in line:gmatch"[^,]+" do
+        table.insert(fields, tonumber(field) or field)
+    end
+    table.insert(csv, fields)
+end
+
+-- change csv values
+table.insert(csv[1], 'SUM')
+for i=2,#csv do
+    local sum=0
+    for _, val in ipairs(csv[i]) do
+        sum = sum + val
+    end
+    table.insert(csv[i], sum)
+end
+
+-- Save
+local fileHandler = io.open('file.csv', 'w')
+for NR, fields in ipairs(csv) do
+    fileHandler:write(table.concat(fields,","), "\n")
+end

Task/CSV-data-manipulation/Lua/csv-data-manipulation.lua

@@ -1,31 +0,0 @@
-local csv={}
-for line in io.lines('file.csv') do
-    table.insert(csv, {})
-    local i=1
-    for j=1,#line do
-        if line:sub(j,j) == ',' then
-            table.insert(csv[#csv], line:sub(i,j-1))
-            i=j+1
-        end
-    end
-    table.insert(csv[#csv], line:sub(i,j))
-end
-
-table.insert(csv[1], 'SUM')
-for i=2,#csv do
-    local sum=0
-    for j=1,#csv[i] do
-        sum=sum + tonumber(csv[i][j])
-    end
-    if sum>0 then
-        table.insert(csv[i], sum)
-    end
-end
-
-local newFileData = ''
-for i=1,#csv do
-    newFileData=newFileData .. table.concat(csv[i], ',') .. '\n'
-end
-
-local file=io.open('file.csv', 'w')
-file:write(newFileData)