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Processing a file of records, splitting each record
Input / Output example from a Well House Consultants training course
More on Input / Output [link]
Source code: skill_lister Module: U110
--[[
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]$ ]] Learn about this subject
This module and example are covered on the following public courses:
* Learning to program in Lua * Lua Programming * Lua Programming Also available on on site courses for larger groups Books covering this topic
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This example comes from our "Input / Output" training module. You'll find a description of the topic and some
other closely related examples on the "Input / Output" module index page.
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