Multiline Capture Trigger and Lua Tables

Posted by Strazor on Sun 03 Jan 2016 12:11 AM — 5 posts, 24,090 views.

Strazor USA Sun 03 Jan 2016 12:11 AM #0

After reading the Multiline Trigger Capture FAQ (http://mushclient.com/forum/?id=7794#37) I've had success capturing the data I need into a LUA table. Now I'm looking for a way to strip that data down and only capture one column of information.

Here is the LUA Table Output


  1 red        Dread Guardian       201 Warrior    Giant        12 May 2013
  2 green    Dread Guardian       201 Warrior   Vampire    02 Jan 2016
  3 blue      Eclipse Lord             201 Cleric      Human      08 Dec 2015
  4 purple   Haze Succubus       201 Mage       Human      25 Sep 2014

What I want to do is extract the names of the colors and put them into another table (I don't need the other data from the multiline capture).

The output I'm wanting would look like this


red
green
blue
purple

Any thoughts on how to parse the data this way?

Nick Gammon Australia Forum Administrator Sun 03 Jan 2016 03:32 AM #1

Assuming your table data looks exactly like that (which I reproduce in my test) then a simple string.match will do it:


tbl = {
  "red        Dread Guardian       201 Warrior    Giant        12 May 2013",
  "green    Dread Guardian       201 Warrior   Vampire    02 Jan 2016",
  "blue      Eclipse Lord             201 Cleric      Human      08 Dec 2015",
  "purple   Haze Succubus       201 Mage       Human      25 Sep 2014 "
}

for k, v in pairs (tbl) do   -- k = key, v = value
  colour = string.match (v, "^%a+")
  if colour then
    print (colour)
  end -- if
end -- for

Output:


red
green
blue
purple

Documentation for Lua string matching:

http://www.gammon.com.au/scripts/doc.php?lua=string.find

Strazor USA Sun 03 Jan 2016 03:45 AM #2

Thanks Nick. My issue now is that the data I listed does not have a key value. The numbers (1,2,3,4) are from the Multiline Trigger I captured. is it possible to create the table with Keys before I capture the data or should I just copy the data to create a new table?

Fiendish USA Global Moderator Sun 03 Jan 2016 11:54 AM #3

Nick already doesn't actually use the table key for anything. The pairs iterator will work for a non-keyed table too so you don't have to do anything and can just use Nick's example directly. If it makes you feel better about the code, you can change "pairs" to "ipairs". It will most likely do exactly the same* thing for your case, but will be semantically more correct.

This peers into one of the more interesting aspects of Lua language, which is that tables are a melange of both key-value dictionaries and ordered-value lists, and you can mix the two into the same table, because really all non-keyed table entries are just automatically given numeric keys.

Try doing each of the following in a Lua script and see how the results differ:


-- using pairs

> for k,v in pairs({"hello", "goodbye"}) do print(k,v) end
1	hello
2	goodbye

> for k,v in pairs({["3"]="foo", "hello", "goodbye"}) do print(k,v) end
1	hello
2	goodbye
3	foo

-- 1 and "1" are different types, so both get put into the table
> for k,v in pairs({["1"]="foo", "hello", "goodbye"}) do print(k,v) end
1	hello
2	goodbye
1	foo

-- using ipairs

-- "1" is ignored, because it's not a number and ipairs only does numbered entries
> for k,v in ipairs({["1"]="foo", "hello", "goodbye"}) do print(k,v) end
1	hello
2	goodbye

> for k,v in ipairs({[3]="foo", "hello", "goodbye"}) do print(k,v) end
1	hello
2	goodbye
3	foo

-- 1="foo" gets overruled by "hello" being the first non-keyed value, because the latter takes priority
> for k,v in ipairs({[1]="foo", "hello", "goodbye"}) do print(k,v) end
1	hello
2	goodbye

-- ipairs stops at the first gap in numbers
-- since there is no 3, it never sees 4
> for k,v in ipairs({[4]="foo", "hello", "goodbye"}) do print(k,v) end
1	hello
2	goodbye

* - I think there may be some small risk that using pairs instead of ipairs on a non-keyed table could potentially return the results out of order, though? Not sure how real that memory is.

Nick Gammon Australia Forum Administrator Sun 03 Jan 2016 08:48 PM #4

Quote:

I think there may be some small risk that using pairs instead of ipairs on a non-keyed table could potentially return the results out of order, though?

Correct. I meant to use ipairs, but pairs will work. I believe that Lua tables actually have a numeric and non-numeric part, so that pairs would (in most cases) return keys in sequence. It switches to the non-numeric part for non-numbers (obviously) and also if there is a large gap in the number sequence.

Quote:

My issue now is that the data I listed does not have a key value.

You can generate keys by doing a table.insert for each line, which will just generate keys starting at 1.

http://www.gammon.com.au/scripts/doc.php?lua=table.insert