help with local macros

[abdelilah arredouani]

Dear all,
I would like to create several boxplots at once and combine them. i found the code below and it works very well. can some one help me understand the different sections. i understand the foreach command but i am confused about the rest mainly
local names `names' graph`j'
local j

Thanks in advance

local j = 1
local names
foreach var of varlist A-X {
     graph box  `var', name(graph`j')
     local names `names' graph`j'
     local j
}

graph combine `names'

Stata 15.1 Mac

[Nick Cox]

Every time you create a new graph you add its name to the list of names so far. Once the loop is done you have a list of all the names to feed to graph combine.

The first command blanks out the macro just in case it exists and contains irrelevant text.

That said the line

local j

looks wrong to me.

It it would be better as

local ++j

[abdelilah arredouani]

yourare right Nick. it is ++j. but what does ++ mean?

[Nick Cox]

help macro

[Nick Cox]

help macro

explains. The value of the local is bumped up (incremented by 1).