--[[

Take a file that contains a whole series of
skills for each person listed and come up
with a list of skills, with each person who
has the particular skill listed under the
skill name

This is a classic example of an application that
takes a file keyed on one value and turns it
around - sorting out lists of the original keys
for each value within the incomeing record.

]]

fhand,errcode =
      io.open("/home/trainee/requests.xyz","r")
if (fhand == nil) then
        print ("Input file: ",errcode)
else

skl = {}
while true do
        line = fhand:read()
        -- which is nicer than:
        -- line = fhand.read(fhand)

        if line then
        s,e,name,skills =
                string.find(line,"^(%S+)(.*)")
        for x in string.gmatch(skills,"(%S+)") do
                -- io.write (name," loves ",x,"\n")
                if skl[x] then
                skl[x][#skl[x]+1] = name
                else
                skl[x] = {}
                end
                end
        else
        break

        end -- if line

end -- while

--[[
Sort in by the new keys (which are
named) and also within each list for
those items (an indexed or numbered
table)
]]

----------------------------------
-- CANNOT sort associative members
-- so sort an indexed list of keys
----------------------------------

langs = {}
for key,value in pairs(skl) do
        langs[#langs+1] = key
        end
table.sort(langs)

for key,value in ipairs(langs) do
        print (langs[key])
        value = skl[langs[key]]
---------------------------------
-- CAN sort indexed list of names
---------------------------------
        table.sort(value)
        for k2,person in ipairs(value) do
                print (" .... ",person)
                end
        end

end -- file opening error test

--[[ Sample Output

[trainee@easterton al]$ lua skill_lister
ASP
 .... delia
 .... ethel
 .... florence
 .... hazel
 .... jenny
 .... leane
 .... nina
 .... olivia
 .... petra
 .... queenie
 .... rita
 .... venus
 .... wendy
 .... xena
 .... zoe
Java
 .... barry
 .... cherry
 .... david
 .... delia
 .... ed
 .... florence
 .... fred
 .... graham
 .... harry
 .... iris
 .... ivan
 .... john
 .... ken
 .... leane
 .... len
 .... morris
 .... nigel
 .... peter
 .... rupert
 .... tina
 .... tommy
 .... ulsyees
 .... uva
 .... venus
 .... xavier
 .... xena
 .... zachary
MySQL
 .... adam
 .... charles
 .... cherry
 .... ethel
 .... fred
 .... gloria
 .... iris
 .... ivan
 .... kerry
 .... len
 .... margaret
 .... olivia
 .... orpheus
 .... queenie
 .... rupert
 .... sally
 .... uva
 .... victor
 .... wendy
 .... yollanda
 .... zachary
PHP
 .... barry
 .... delia
 .... ed
 .... florence
 .... harry
 .... hazel
 .... john
 .... leane
 .... morris
 .... nigel
 .... olivia
 .... peter
 .... quentin
 .... rita
 .... steve
 .... ulsyees
 .... uva
 .... william
 .... xavier
 .... xena
 .... yuri
 .... zoe
Perl
 .... adam
 .... barry
 .... charles
 .... cherry
 .... david
 .... ed
 .... ethel
 .... fred
 .... gloria
 .... graham
 .... hazel
 .... iris
 .... ivan
 .... jenny
 .... john
 .... ken
 .... kerry
 .... leane
 .... len
 .... margaret
 .... morris
 .... nigel
 .... nina
 .... peter
 .... petra
 .... queenie
 .... quentin
 .... rita
 .... sally
 .... steve
 .... tommy
 .... ulsyees
 .... uva
 .... venus
 .... victor
 .... wendy
 .... william
 .... xavier
 .... xena
 .... yuri
 .... zoe
Python
 .... adam
 .... barry
 .... harry
 .... ken
 .... leane
 .... nigel
 .... olivia
 .... rupert
Ruby
 .... charles
 .... cherry
 .... ed
 .... florence
 .... hazel
 .... ivan
 .... jenny
 .... kerry
 .... len
 .... margaret
 .... nina
 .... orpheus
 .... petra
 .... queenie
 .... quentin
 .... rita
 .... steve
 .... tina
 .... venus
 .... victor
 .... william
 .... yollanda
 .... zoe
Tcl/Tk
 .... adam
 .... barbara
 .... charles
 .... david
 .... ethel
 .... gloria
 .... graham
 .... iris
 .... ivan
 .... ken
 .... kerry
 .... margaret
 .... morris
 .... nina
 .... orpheus
 .... petra
 .... quentin
 .... sally
 .... steve
 .... tina
 .... victor
 .... wendy
 .... yollanda
 .... yuri
 .... zachary
XML
 .... barry
 .... delia
 .... fred
 .... gloria
 .... jenny
 .... john
 .... margaret
 .... orpheus
 .... petra
 .... sally
 .... tommy
 .... xena
 .... yuri
[trainee@easterton al]$

]]