sorting a table

Posted by Renny on Sat 25 Apr 2015 07:42 AM — 5 posts, 18,696 views.

Renny Canada Sat 25 Apr 2015 07:42 AM #0

I want to sort a table based on two comparison operations.


t = { 
[1] = { fruit = pear, color = red, rank = 0 }, 
[2] = { fruit = apple, color = orange, rank = 1 }, 
[3] = { fruit = orange, color = green, rank = 2 }, 
[4] = { fruit = potatoe, color = black, rank = 1 },
}

I want to first sort the table by rank numerically, and then sort it by color alphabetically.

So the order would be,


1 = orange, green, 2
2 = potatoe, black, 1
3 = apple, orange, 1
4 = pear, red, 0

I am aware of this function,



table.sort(t, function(a, b) return a.rank > b.rank end)

but don't know how to do a more complicated sort.

Fiendish USA Global Moderator Sat 25 Apr 2015 01:24 PM #1

Maybe

table.sort(t, function(a, b) if a.rank == b.rank then return a.color > b.color else return a.rank > b.rank end)

Renny Canada Sat 25 Apr 2015 04:14 PM #2

Fiendish said:

Maybe

table.sort(t, function(a, b) if a.rank == b.rank then return a.color > b.color else return a.rank > b.rank end)

gives me a syntax error

unexpected symbol near ')'

Fiendish USA Global Moderator Sat 25 Apr 2015 06:16 PM #3

Fixing the syntax error left as a learning exercise for the reader. :) If you uncombine the comparison function from the sort invocation, as in


function mysort(a,b)
...

table.sort(t, mysort)

The fix should become obvious.

Also in your table you need to put the colors and fruits in quotation marks, brcause they are strings.

Also potato doesn't end with an e and isn't a fruit.

Renny Canada Sat 25 Apr 2015 08:33 PM #4

Fiendish said:

Also potato doesn't end with an e and isn't a fruit.

Thx this works perfect