World: r3wp

someop [ 1 1 2 3 4 ] [ 1 ] 
== [ 1 2 3 4 ]

exclude

oh .. it's alter

but it will add them if they're not there.

that's okay ... I need to remove all elements where there's only 
one of them

all patients who have had more than one office visit over the past 
year with a diagnosis of hypertension :)

oh ... you want  'UNIQUE

why do you need the second argument?

unique [ 1 1 2 3 4 ]
== [ 1 2 3 4 ]

no .. I want alter

set1: [ 1 2 3 1 2 3 4 ] <= need to remove 4
set2: unique copy set1
alter set1 set2

no need for copy... all "set" functions copy.

can never remember which copy and which inline

the above returns...  [1 2 3 4] on my test.

sorry  [1 2 3 2 3 4]

well, that's no good is it!

so you want to remove singletons from a block?

yes .. so why isn't alter doing that?

actually I want to remove one of each

ok so given:    [ 1 2 3 1 2 3 1 4 ] 
what is desired result?

[ 1 2 3 ]

maybe I do want exclude and then unqiue

no .. exclude operates on sets

if you know [4] then that will work

blk:  [ 1 2 3 1 2 3 1 4 ]
unique exclude blk [4]

I don't know

ok working on a solution (I like these quick riddles)

I'm going to have to use a loop :(

I don't know why subtract does not work on blocks

foreach el set2 [ remove find set1 el ]

I tried yours and it didn't seem to work... but this definitely does:

c: 0
blk:  [ 1 2 3 1 2 3 1 4 ]

unique remove-each i copy blk [ c: c + 1 not find (at blk c + 1) 
i]

I can't see why mine won't work ...

since set2 is a unique version of set1, it will always find and always 
remove

I've long considered + and - on blocks to be useful... but, would 
others agree?

YES!

go for it!

though I don't mind if we use 'subtract and 'add

They're the same.

there is also a really usefull missing "set" function


duplicates:   returns items in a series present multiple times in 
that series.


without this function, right now there are many missing combinations.

to get singletons:

exclude blk duplicates block

next you'll be asking for the ability to create combinations and 
permutations!

well, AFAIK duplicates is probably the single most frequently re-requested 
series function I've seen in the years.

so return those in a block where there exists more than one?

yep.

which is essentially what I was trying to do above

what instances have you needed this?

but its so usefull in simplifying many other loops and algorithms.

when managing data sets, you often want to know what is unique "within" 
that set.   

duplicates and singletons are often-required things you want to know 
about a data set.

i guess make a wish on curecode for R3

yes... I just thought about that.

I will.

Has anyone a simple algorithm for calculating the last day of a month? 
 Or is a lookup table easiest?


get-end-month: func [ d [date!] /local tmp ][ tmp: d while [ tmp/month 
= d/month ][ tmp: tmp + 1 ] tmp ]

get-end-month: func [ d [date!] /local tmp ][ tmp: d while [ tmp/month 
= d/month ][ tmp: tmp + 1 ] tmp - 1 ]