Omnimaga
Calculator Community => TI Calculators => Lua => Topic started by: pianoman on July 15, 2011, 01:01:23 pm
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Hi again!
Just wondering, how do you use the sort feature in Lua for tables?
Thank you very much!
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> mytable = {"omnimaga", "pianoman", "ephan"}
> -- When order alphabetically, it should be "ephan", "omnimaga", "pianoman"
> table.sort(mytable)
> = a[1]
ephan
> = a[2]
omnimaga
> = a[3]
pianoman
table.sort() sorts a table of strings alphabetically or numerically, if it is table of integers:
> myinttable = {4,2,1,3}
> table.sort(myinttable)
> return myinttable[1]
1
> return myinttable[2]
2
> return myinttable[3]
3
> return myinttable[4]
4
More information can be found here (http://lua-users.org/wiki/TableLibraryTutorial).
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Interesting... could be very useful.
Thanks, ephan!
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This is a direct quote from http://lua-users.org/wiki/TableLibraryTutorial , which I describes the usage very good:
table.sort(table [, comp])
Sort the elements of a table in-place (i.e. alter the table).
> t = { 3,2,5,1,4 }
> table.sort(t)
> = table.concat(t, ", ") -- display sorted values
1, 2, 3, 4, 5
If the table has a specified size only the range specified is sorted, e.g.,
> t = { 3,2,5,1,4; n=3 } -- construct a table with user size of 3
> table.sort(t) -- sort will be limited by user size
> = table.concat(t, ", ") -- only specified size is concatenated as well
2, 3, 5
A comparison function can be provided to customise the element sorting. The comparison function must return a boolean value specifying whether the first argument should be before the second argument in the sequence. The default behaviour is for the < comparison to be made. For example, the following behaves the same as no function being supplied:
> t = { 3,2,5,1,4 }
> table.sort(t, function(a,b) return a<b end)
> = table.concat(t, ", ")
1, 2, 3, 4, 5
We can see if we reverse the comparison the sequence order is reversed.
> table.sort(t, function(a,b) return a>b end)
> = table.concat(t, ", ")
5, 4, 3, 2, 1
Edit: Ephan's post is also very informative
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Interesting... could be very useful.
Thanks, ephan!
The typical example is the classic program when the user will enter N numbers and you have to sort them and print them out. I just coded this:
n = io.read()
n = tonumber(n)
f = {}
for i=1,n do
a = io.read()
table.insert(f, a)
end
table.sort(f)
print("")
for i=1,n do
print(f[i])
end
This gets a variable N as input from the user, then it reads N numbers. After this, it prints them ordered.