1. Manipulating Locals
   1. Remove duplicates
   2. Add/Remove Elements
   3. Union and intersection
   4. Sorting

Manipulating Locals

Remove duplicates

1. Use the list uniq macro list functionality

    local vars state county county
    loc nodups : list uniq vars
   

    display `nodups'
    . state county
   

Add/Remove Elements

Removing elements of a local is easy.

1. Create a local (minus) with the elements you want to remove

    local vars a b c
    local minus a
   

    display `vars'
    . a b c
   

2. Use the macro list functionality: list with a minus

    local vars : list vars - minus
   

    display `vars'
    . b c
   

Union and intersection

Another useful tool is taking the common and different elements between two locals

local x state county
local y county tract

1. For unions use | (like in x “or” y)

    local union : list x | y
   

    display `union'
    .  state county tract
   

2. For intersections use & (like in x “and” y)

    local intersection : list x & y
   

    display `intersection'
    .  county
   

Sorting

Sometimes we want to sort elements of a local

1. Use sort macro list functionality

    local unordered b c a
    local ordered : list sort unordered
   

    display `ordered'
    . a b c