CODEWITHSUNDEEP
luaiteratorlua-table
PirateApp
PirateApp

Reputation: 6220

How do I achieve this loop in Lua without external libraries

I am a newbie to Lua so kindly bear with me. I have 2 csv strings in Lua

a= '1,2,3,4,5'

represents the index and 

b='this,needs,to,be,matched:with,every,single,row,here:'

The rows are separated by a ':' character instead of newline

Expected output

1,this,2,needs,3,to,4,be,5,matched
1,with,2,every,3,single,4,row,5,here

I tried iterating through the them separately with the following code

local result= {}
local u = unpack or table.unpack
for values in string.gmatch(values_csv, '([^:]+)') do
    local data = {}
    for column1,column2 in string.gmatch(values, '([^,]+)'),string.gmatch(keys, '([^,]+)') do
        print(column1, column2)
    end
end

For some reason the second one is always nil. I cant find a zip function similar to Python in Lua without external libs. How do I iterate both simulatenously. Thanks for the help

Upvotes: 1

Views: 90

Answers (2)

tonypdmtr
tonypdmtr

Reputation: 3225

A variation of Egor's solution to get the output as you asked:

a = '1,2,3,4,5'
b = 'this,needs,to,be,matched:with,every,single,row,here:'

for line in b:gmatch '[^:]+' do
  local idx = a:gmatch '%d+'
  local ans = {}
  for v in line:gmatch '[^,]+' do
    ans[#ans+1] = idx()
    ans[#ans+1] = v
  end
  print(table.concat(ans,','))
end

Upvotes: 2

Egor Skriptunoff
Egor Skriptunoff

Reputation: 974

local keys = '1,2,3,4,5'
local values_csv = 'this,needs,to,be,matched:with,every,single,row,here:some,values,,are,absent:'

for values in values_csv:gmatch'[^:]+' do
   local data = {}
   local keys_iter = keys:gmatch'[^,]+'
   for value_column in (values..','):gmatch'([^,]*),' do
      print(keys_iter(), value_column)
   end
end

Upvotes: 1

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