OpenEuphoria

2. Re: My first program: sublime (reverse of "extract" function)

• Posted by DerekParnell (admin) May 18, 2013
• 2484 views

Why go to this trouble? Just keep a copy of the original list, but I'm not sure why one even needs to do that. The sort() function does not change, in anyway, the input list.

 
sequence Unsorted = {0.5, 0.2, 0.4, 0.3, 0.1, 0.5} 
sequence CopyList = Unsorted 
sequence Sorted = sort(Unsorted) 
if equal(Unsorted, CopyList) then  puts(1, "test passed!\n")  end if 

4. Re: My first program: sublime (reverse of "extract" function)

• Posted by DerekParnell (admin) May 18, 2013
• 2456 views

Yeah .. sorry. I did reply around 2:00AM after a glass of wine or two, so I was a little bit 'tired'.

My main point was to explain that in the Euphoria Programming Language, a routine can never affect the contents of any of its parameters beyond the scope of the routine.

For example:

function XY( atom PA, sequence PB) 
 
    atom LC 
 
    -- This routine modifies the parameter values supplied, 
    -- but note that the modifications only last for the duration 
    -- of this routine. That is to say, any modifications 
    -- done inside a routine, never affect the supplied data 
    -- outside of the routine. 
 
    LC = PA                -- Save the number that was given to me 
    PA = length(PB)        -- Get the length of the sequence that was given 
    PB = append(PB, LC)    -- Add the original number to the end of the list 
    PB = append(PB, PA)    -- Add the original list length to the end of the list 
 
    return PB              -- return the resulting list. 
end function 
 
atom GA = 42 
sequence GB = {1,2,3,4,0} 
 
? XY(GA, GB) --> {1,2,3,4,0,42,5} 
? GA --> 42 
? GB --> {1,2,3,4,0} 
 
-- The data in GA and GB have not been 'permanently' changed. 
 

6. Re: My first program: sublime (reverse of "extract" function)

• Posted by jimcbrown (admin) May 19, 2013
• 2410 views

Why can't you keep a copy of the original list? What type of processing are you doing that makes this solution unsuitable?

8. Re: My first program: sublime (reverse of "extract" function)

• Posted by jimcbrown (admin) May 19, 2013
• 2406 views

sequence InputData = {0.01, 0.05, 0.08, 0.03, 0.02} 
sequence OutputData = sort(InputData) 
sequence OriginalOrder = sublime(InputData, OutputData) 
for i = 2 to length(OutputData) do 
    OutputData[i] *= 1 - OutputData[i-1] 
end for 
OutputData = extract(OutputData, OriginalOrder) 

I think I get it. Your example can still be implemented as:

sequence InputData = {0.01, 0.05, 0.08, 0.03, 0.02} 
sequence OutputData = 1 - InputData[2..$] 

But I think your point is clear - you don't want to merely use your sorted input data for a task and then reuse the unsorted version later. You don't want to just sort the output data either. You need to sort the input data for a task, then "unsort" the output data such that the each element of the output data is in the same position as the corresponding element in the original unsorted input data.

If every element is unique in the input data, and every element is unique in the output data, then you could just use mapping(). But that probably isn't true.

I'd go with optimal.

10. Re: My first program: sublime (reverse of "extract" function)

• Posted by jimcbrown (admin) May 19, 2013
• 2396 views

sequence InputData = {0.01, 0.05, 0.08, 0.03, 0.02} 
sequence OutputData = 1 - InputData[2..$] 

I just meant that particular example. This won't help your real code though, so it's not worth delving into.

You can do this within the stdlib.

function compare_saving_index(object x, object y) 
	return compare(x[2], y[2]) 
end function 
 
public function sort_with_index(sequence s, integer order = NORMAL_ORDER) 
	sequence x = repeat(0, length(s)) 
	for i = 1 to length(x) do 
		x[i] = {i, s[i]} 
	end for 
	return custom_sort(routine_id("compare_saving_index"), s, order) 
end function 
 
public function get_indexes_from_sorted(sequence s) 
	return vslice(s, 1) 
end function 
 
public function get_values_from_sorted(sequence s) 
	return vslice(s, 2) 
end function 
 
sequence unsortedinput = ... 
sequence sortedandindex = sort_with_index(unsortedinput) 
sequence sortedinput = get_values_from_sorted(sortedandindex) 
sequence idx = get_indexes_from_sorted(sortedandindex) 
sequence sortedoutput = ... sortedinput ... 
sequence unsortedoutput = extract(sortedoutput,idx) 

12. Re: My first program: sublime (reverse of "extract" function)

• Posted by useless_ May 19, 2013
• 2415 views

I don't think that's quite what was meant. If the original list was sorted by a column, sorttok would re-sort by whatever other column(s) was desired, and then sorttok again on the original column(s) to put it all back in original order.

useless

14. Re: My first program: sublime (reverse of "extract" function)

• Posted by useless_ May 19, 2013
• 2432 views

Did all that happen after the post i responded to?

useless

16. Re: My first program: sublime (reverse of "extract" function)

• Posted by useless_ May 19, 2013
• 2299 views

Well, good thing i used the conditional "if" in my statement. I guess this is turning into another one of those threads where no matter what i say, we'll go on for days like this, eh?

useless

18. Re: My first program: sublime (reverse of "extract" function)

• Posted by useless_ May 20, 2013
• 2286 views

Well,

And i didn't think that is what was meant, that's true. And i did say "if" in the second statement:

So i don't understand what your problem with it is.

useless

20. Re: My first program: sublime (reverse of "extract" function)

• Posted by useless_ May 20, 2013
• 2275 views

As was i, trying to be helpful.

useless

22. Re: My first program: sublime (reverse of "extract" function)

• Posted by SocIoDim May 22, 2013
• 2130 views

tag_sort() is my sublime() from first message? I think I understand your point. Yes, it is possible, but not relevant to my situation. The only advantage of this approach: it saves memory. The downside: I need to rewrite the function that operates on sorted data. However, the economy does not interest me. By the way, the function is already written, but it is more complicated than multiplication in above example, so I do not want to make it less readable even at a tiny fraction. Nevertheless, thank you very much for regard.