What is the best way to have a function sort an associative array by key?  The following yields a conversion error.

double[string] aa_sort(double[string] aa) {
  return aa.keys.sort;
}

On 11/23/12, dsmith <ds@nomail.com> wrote:
> What is the best way to have a function sort an associative array by key?  The following yields a conversion error.
>
> double[string] aa_sort(double[string] aa) {
>    return aa.keys.sort;
> }

Hashes are unordered, you can't sort them by key because they don't preserve any order during insertion/removal. You can alternatively return a sorted array:

string[] keys_sorted(double[string] aa) {
    string[] keys = aa.keys;
    sort(keys);  // from std.algorithm;
    return keys;
}

On 11/23/2012 07:09 PM, dsmith wrote:
> What is the best way to have a function sort an associative array by
> key?  The following yields a conversion error.
>
> double[string] aa_sort(double[string] aa) {
>    return aa.keys.sort;
> }
>
>

A hash table is unsorted by definition. What is it that you want to do exactly?

The following will generate a newly allocated dynamic array of key-value pairs, sorted by key:

import std.algorithm, std.typecons;

Tuple!(string, double)[] aa_sort(double[string] aa){
    typeof(return) r=[];
    foreach(k,v;aa) r~=tuple(k,v);
    sort!q{a[0]<b[0]}(r);
    return r;
}

On Friday, 23 November 2012 at 18:24:07 UTC, Timon Gehr wrote:
> On 11/23/2012 07:09 PM, dsmith wrote:
>> What is the best way to have a function sort an associative array by
>> key?  The following yields a conversion error.
>>
>> double[string] aa_sort(double[string] aa) {
>>   return aa.keys.sort;
>> }
>>
>>
>
> A hash table is unsorted by definition. What is it that you want to do exactly?
>
> The following will generate a newly allocated dynamic array of key-value pairs, sorted by key:
>
> import std.algorithm, std.typecons;
>
> Tuple!(string, double)[] aa_sort(double[string] aa){
>     typeof(return) r=[];
>     foreach(k,v;aa) r~=tuple(k,v);
>     sort!q{a[0]<b[0]}(r);
>     return r;
> }

Suppose the string is of the format 201207, 21208, ...
So aa["201207"] == 123.45

How do you parse the tuple for the key and the value?

On 11/23/2012 07:48 PM, dsmith wrote:
> On Friday, 23 November 2012 at 18:24:07 UTC, Timon Gehr wrote:
>> On 11/23/2012 07:09 PM, dsmith wrote:
>>> What is the best way to have a function sort an associative array by
>>> key?  The following yields a conversion error.
>>>
>>> double[string] aa_sort(double[string] aa) {
>>>   return aa.keys.sort;
>>> }
>>>
>>>
>>
>> A hash table is unsorted by definition. What is it that you want to do
>> exactly?
>>
>> The following will generate a newly allocated dynamic array of
>> key-value pairs, sorted by key:
>>
>> import std.algorithm, std.typecons;
>>
>> Tuple!(string, double)[] aa_sort(double[string] aa){
>>     typeof(return) r=[];
>>     foreach(k,v;aa) r~=tuple(k,v);
>>     sort!q{a[0]<b[0]}(r);
>>     return r;
>> }
>
> Suppose the string is of the format 201207, 21208, ...
> So aa["201207"] == 123.45
>
> How do you parse the tuple for the key and the value?

tpl[0] is the key and tpl[1] is the value in this case.