List Commands Library for 50g

[John Keith]

(08-24-2017 10:25 PM)Gilles59 Wrote:  

(08-13-2017 04:59 PM)DavidM Wrote:  Combining the two lists:

Code:

{ "longest" "longer" "long" }
{ 7 6 4 }

into the needed format is simple enough with:

Code:

DUP SIZE LSDIV SWAP ADD

...which then leaves it to the user to choose which sort they want to use. After sorting, the combined list elements can be easily separated again if needed:

Code:

LCLLT 2 LSDIV LRLL EVAL

With gofer list you can do

Zip SORT Unzip

Code:


Zip        xs ys -> xss        { 1 2 3 } { A B C } Zip
                    -> { { 1 A } { 2 B } { 3 C } }

Unzip        xss -> xs ys        { {1 A} {2 B} {3 C} } Unzip
                    -> { 1 2 3 } { A B C }

There are also Zip3 and Unzip3 (but no ZipN)

There is also a Sort command in GoferList with the syntax :
{ my list } << how to sort >> Sort
but if the idea seems goods it is not stable at all and crash easily the system. In our exemple could be
{ "longest" "longer" "long" } << SIZE >> Sort
But this dont work and crash badly : DONT TRY THIS
But you can easily write your own command for this syntax in User RPL. Idea :

Code:

« { "longest" "long" "longer" } 
   DUP « SIZE » DOLIST SWAP Zip SORT Unzip NIP »

I imagine a DOSORT command :
{ list to sort } << How to sort>> DOSORT

Internally The DOSORT program could use the native SORT

example

{ 1. 123 "xyz" "abc" 'y=a*x*+b' } << TYPE >> DOSORT
{ -1 5 66 -89 33 } << ABS >> DOSORT
{ "Z" "a" "B" "d" } << UPCASE >> DOSORT

etc.

The reason GoferLists' Sort command crashes in this case is that it is meant to work in a slightly different manner. The program used by your code is an objective function whereas the program required by Sort is a comparison operator. If you use the program \<< SIZE SWAP SIZE > \>> Sort will function correctly. Of course Sort should not crash the calculator under any circumstances and it is also quite slow.

Coincidentally, I have written a short program that is similar to yours which I call GSORT as in General-purpose sort. It uses commands from the ListEx library rather than GoferLists, and works exactly like your proposed DOSORT command:

Code:

\<< \-> p
    \<< DUP 2.
        \<<p EVAL SWAP 2. \->LIST \>>
        DOLIST SORT LCLLT 2 LSDIV 2. GET
    \>>
\>>

Note that either program will work with LSORT provided that the list you are sorting does not contain a mix of exact integers and reals.

John