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- Subject: Re: lhs and rhs in table.sort
- From: iain morland <iain@...>
- Date: Mon, 24 Aug 2015 22:00:42 +0100
Thank you Oliver; you are quite right about the function requiring an array.
I read the description of table.sort in PiL but am still unsure over “lhs" and “rhs". I couldn’t see those mentioned anywhere (in the whole book - unless Robert can please correct me!). How would a person know to use myArray[lhs] < myArray[rhs] in the first place? Are there other terms that might be used in place of “lhs” and “rhs” to do other things with the array? I feel that I am missing a crucial piece of understanding about this.
Regards
iain
>
> Hi,
>
> table.sort is described in chapter 20.2 of Programming in Lua. The
> optional function argument is being called with two elements of the
> table to be sorted and has to return true if the first of its arguments
> shall come first in the sorted table.
>
> Note that the function is actually only defined for an array, which is a
> table with subsequent numbers as indices.
>
> --
> Oliver
>
> Am 24.08.2015 um 16:54 schrieb iain morland:
>> Greetings all,
>>
>> I am researching the different compare functions that are available for use with the table.sort function.
>>
>> After some searching online, I was able to use the following as the second argument in table.sort:
>>
>> function(lhs,rhs) return myTable[lhs] < myTable[rhs] end
>>
>> In turn, I used this to sort another table of the same size like so:
>>
>> table.sort(otherTable,function(lhs,rhs) return myTable[lhs] < myTable[rhs] end)
>>
>> However I couldn’t find reference to the use of "lhs" or “rhs" in the Lua documentation, and feel frustrated that I don’t fully understand what’s happening in the above code.
>>
>> So I have two questions:
>>
>> 1. Could anyone explain (or direct me to an explanation of) the different compare functions that can be used with table.sort?
>>
>> 2. Are there any documented examples of how these functions work when sorting one table by the result of sorting another table?
>>
>> Thanks in advance
>> iain
>