csv.lua
The file is part of the BURN project (learing multi-objective rules).
Because learning is not the filling a pail, but the lighting of a fire.
local Lib= require("lib")
local split, sub, scan =
Lib.split, Lib.sub, Lib.scan
local Csv={}csv(file: string)
Iterator. Kills comments, white space. If any line ends in ,,
then we join it to the next one. Resulting lines
are then split on , and cells are converted to
strings or numbers as appropriate.
Note that if the first row marks tha a column
is to be ignored
(by have a column name containing ?) then
all such columns are ignored. The result
non-ignored rows of cells are returns, one at a time.
local function Csv(file)
local stream = io.input(file)
local use, cache, todo = {}, {}, io.read()
return function ()
while todo do
local txt = todo:gsub("[\t\r ]*","") -- no spaces
:gsub("#.*","") -- no comments
todo = io.read()
cache[ #cache+1 ] = txt -- accumulate lines until...
if sub(txt,-1) ~= "," then -- ... until end of row
local txts = table.concat(cache)
if string.len(txts) > 0 then -- non-empty lines
local row,cells
cache, row, cells = {}, {}, split(txts)
if #use==0 then -- this is our first loop
for i= 1,#cells do -- so get the columns we want
if not string.find( cells[i], "?" )
then use[ #use+1 ] = i end end end
for i= 1,#use do -- grab the columns we want
row[ #row+1 ] = scan( cells[use[i]] ) end
return row end end
end
io.close(stream) end
end
return Csv