PrettyTable - in Lua (just a test, not a full fledged module, or as powerful as the Py counterpart)

prettytable.lua

-- Tue Apr 22 15:46:42 IST 2014
-- Aniruddha. A
--
-- just to see how much effort it is to simulate Py like PrettyTable module 

local function max(a,b) return a < b and b or a end
local function printf(...) return io.stdout:write(string.format(...)) end

function pad(s, width, padchar)
    local padder = string.rep(padchar or ' ', width)
    if width < 0 then return string.sub(padder .. s, width) end
    return string.sub(s .. padder, 1, width)
end

function calign(s, width)
    local spaces = width - #s
    local x = math.floor(spaces/2)
    return string.rep(' ',x) .. s .. string.rep(' ', width - x - #s)
end

function prettytable(t) 
    assert(t.heading, "Need a `heading' for the table!") -- mandatory table, which determines formatting

    local ncols = #t.heading
    t.width = {}
    for i=1,ncols do 
        t.width[i] = #t.heading[i]
    end

    for j=1,#t do -- each data entry in the table
        for i=1,ncols do  -- as many cols as the heading
            t.width[i] = max(t.width[i], #tostring(t[j][i]))
        end
    end

    -- Print heading 
    printf('\n+')
    for i=1,#t.width do 
        printf('-%s-+', pad('', t.width[i], '-'))
    end
    printf('\n|')
    for i,h in ipairs(t.heading) do 
        printf(' %s |', calign(h, t.width[i])) -- only the header is center aligned 
    end
    printf('\n+')
    for i=1,#t.width do 
        printf('-%s-+', pad('', t.width[i], '-'))
    end
    -- Print the rows
    for i=1,#t do 
        printf('\n|')
        for j,v in ipairs(t[i]) do 
            printf(' %s |', pad(v, t.width[j]))
        end
    end
    -- End
    printf('\n+')
    for i=1,#t.width do 
        printf('-%s-+', pad('', t.width[i], '-'))
    end
    printf('\n')
end

----------------- Test ------------------------

-- User input (TODO: add a neat API )
local tbl = { heading = { 'A', 'Hello', 'World' },
                -- data -- 
                { 101, 222 , 123 },
                { 'an', 'a bad ass str', '1243c' }
            }

prettytable(tbl)

-- TODO: handle the align/justify to left/center or right as a user option 
-- TODO: provide an option to dump a slice of the column like select only one, or more columns