Finding Gaps in Sequence

[Ocean West]

Someone requested on face book a function to find a gap in sequence.

 

Quote

I have a list of numbers such as 1¶2¶3¶6¶7¶8¶12¶13 I need to be able create a text string from this which looks like 1-3, 6-8, 12-13

This is my attempt for that with a While Function

If I were to add this to a custom function i would Replace X with a parameter - also perhaps suggest to do a unique list and sort list on the parameter.

 

While ( 

[ 
x = "1¶2¶3¶6¶7¶8¶12¶13¶16¶17¶18" ; 
y = "" ; 
z = "" ; 
out = "" ;
i = 1 ;
c = ValueCount ( x ) 

] ; 

i ≤ c  ; 

[ 

y = GetValue ( x ; i ) ;

z = case ( 

y+1 = GetValue ( x ; i+1 ) or  y-1 = GetValue ( x ; i+1 ) ; "" ;   "-" & y & "," ) ;

out =  Case ( i = 1 ; y ; Right (out ;1) = "," ; out & y ; out & z ) ; 

i = i+1

] ;
Case( right (out;1) = "," ; Left ( out ; Length (out) -1 ))
)

 

i haven't fully tested so please test it out before use in production - if you see room for improvement it is welcomed  

[comment]

I did this a long time ago - way before While() became available:
https://www.briandunning.com/cf/734

 

[Ocean West]

Much more elegant