How do I build a lookup table?

gbailey · December 4, 2012, 1:22pm

I’m trying to build a lookup table in lua so that when a user selects a particular person, I can return that person’s info. Problem is, I can’t seem to figure out how to access a particular person in the table…

[lua] – The following would normally come from a user’s choice.
local selectedDealer = “Gerald”

dealers = {
dealerName = “Gerald”,
mainPhone = “(512) 555-1212”,
salesPhone = “(512) 555-1212”,
servicePhone = “(512) 555-1212”,
}
dealers = {
dealerName = “Tom”,
mainPhone = “(512) 555-1212”,
salesPhone = “(512) 555-1212”,
servicePhone = “(512) 555-1212”,
}

– The following returns ‘nil’
if table.indexOf( dealers[dealerName], selectedDealer) then
print (“Gerald Found!”)
elseif table.indexOf( dealers[dealerName], selectedDealer) then
print (“Tom Found!”)
else
print (“None found!”)
end[/lua]

Any help would be greatly appreciated!! [import]uid: 64538 topic_id: 33637 reply_id: 333637[/import]

Screaming_Leaf · December 4, 2012, 2:36pm

Well initially it looks like you are overwriting your dealers table; the “Tom” entry is overwriting the “Gerald” entry.

If you want multiple entries try either:

 table.insert(dealers,index)

or

dealers = {{dealerName = "Gerald",  
 mainPhone = "(512) 555-1212",  
 salesPhone = "(512) 555-1212",  
 servicePhone = "(512) 555-1212",  
 },  
 {  
 dealerName = "Tom",  
 mainPhone = "(512) 555-1212",  
 salesPhone = "(512) 555-1212",  
 servicePhone = "(512) 555-1212",  
 }  
 }

or

dealers[#dealers+1] = { dealerName = "Tom", mainPhone = "(512) 555-1212", salesPhone = "(512) 555-1212", servicePhone = "(512) 555-1212", } [import]uid: 94868 topic_id: 33637 reply_id: 133743[/import]

brian-nexus · December 4, 2012, 2:38pm

Try this out

[lua]-- The following would normally come from a user’s choice.
local selectedDealer = “Gerald”

dealers = {{
dealerName = “Gerald”,
mainPhone = “(512) 555-1212”,
salesPhone = “(512) 555-1212”,
servicePhone = “(512) 555-1212”,
},
{
dealerName = “Tom”,
mainPhone = “(512) 555-1212”,
salesPhone = “(512) 555-1212”,
servicePhone = “(512) 555-1212”,
}}

for i = 1, #dealers do
if dealers[i].dealerName == selectedDealer then
print("Name: ",dealers[i].dealerName)
print("Main Phone: ",dealers[i].mainPhone)
print("Sales Phone: ",dealers[i].salesPhone)
print("Service Phone: ",dealers[i].servicePhone)
end
end[/lua]

Notice all I really did was make ‘dealers’ one complete table instead of two, and created two tables within ‘dealers’ for each dealer respectively. Then using dealers[i].dealerName you can get any data on that dealer you need. [import]uid: 40731 topic_id: 33637 reply_id: 133744[/import]

brian-nexus · December 4, 2012, 3:09pm

As far as I know it shouldn’t be a performance problem, how many arrays (dealers) are you planning on having in the database?

I’m working on a project now that uses two tables each with 64 values in them, I have eight for loops running through in steps of eight each at a time with no slow down.

And besides with my experience on tables in the past I’ve found they can be pretty powerful and efficient on a large scale. [import]uid: 40731 topic_id: 33637 reply_id: 133750[/import]

gbailey · December 4, 2012, 3:10pm

That looks like it would take a hit on performance though unless I’m mistaking something?

Originally I was trying to use something like the following, but couldn’t figure out how to make that work either…

[lua]local selectedDealer = “Gerald”

dealers.Gerald = {
mainPhone = “(512) 555-1212”,
salesPhone = “(512) 555-1212”,
servicePhone = “(512) 555-1212”,
}
dealers.Tom = {
mainPhone = “(512) 555-1212”,
salesPhone = “(512) 555-1212”,
servicePhone = “(512) 555-1212”,
}[/lua]

As you can probably tell, I’m just trying to figure out how to create a 2D array, and how to do a quick lookup in that array. [import]uid: 64538 topic_id: 33637 reply_id: 133749[/import]

gbailey · December 4, 2012, 3:33pm

I found this to work, but seems like there should be an easier way to do the comparison…

[lua] local selectedDealer = “Fred”

dealers = {}

dealers[1] = {
dealerName = “Gerald”,
mainPhone = “(512) 555-1212”,
salesPhone = “(512) 555-1212”,
servicePhone = “(512) 555-1212”
}
dealers[2] = {
dealerName = “Tom”,
mainPhone = “(512) 555-1212”,
salesPhone = “(512) 555-1212”,
servicePhone = “(512) 555-1212”
}

– The following returns ‘nil’
if dealers[1].dealerName == selectedDealer then
print (“Gerald Found!”)
elseif dealers[2].dealerName == selectedDealer then
print (“Tom Found!”)
else
print (“None Found!”)
end[/lua] [import]uid: 64538 topic_id: 33637 reply_id: 133752[/import]

Screaming_Leaf · December 4, 2012, 6:31pm

or

[code]
dealers = {}

dealers[“Gerald”] = {
mainPhone = “(512) 555-1212”,
salesPhone = “(512) 555-1212”,
servicePhone = “(512) 555-1212”
}

dealers[“Tom”] = {
mainPhone = “(512) 555-1212”,
salesPhone = “(512) 555-1212”,
servicePhone = “(512) 555-1212”
}

if dealers[dealerName] then
print (dealerName … " Found!")
else
print (dealerName…" Not Found!")
end
[/code] [import]uid: 94868 topic_id: 33637 reply_id: 133780[/import]

bjsorrentino · December 4, 2012, 11:25pm

Screaming Leaf has it correct. Build your table with the dealer names as the keys, and other associated info for that dealer in the key’s unique table. Lua will do a very fast lookup this way, and the structure allows you to add, edit, or delete info about any dealer by looking up his/her key, then specifying the desired sub-key for that dealer.

Brent [import]uid: 200026 topic_id: 33637 reply_id: 133808[/import]

gbailey · December 5, 2012, 6:24am

Thanks, that looks like exactly what I needed! [import]uid: 64538 topic_id: 33637 reply_id: 133858[/import]

Screaming_Leaf · December 4, 2012, 2:36pm