Using quotes in local and global macros in Stata

For some reason I spent a lot of time yesterday doing this: turn a list of variables into a list with doublequotes for each variable, then separated by commas.  I confess I still do not really understand the logic of Stata quotes… and numerous websites suggest they are indeed thinks to be wary of…  Anyway, the reason I did this is because I then wanted to pass ttpcomma into an inlist function, but I could never get it to work (and no, it did not exceed the 10 string variables).  The inlist would not “read” the local, even though it would when I created what I thought was the exact same content separately.

local p “v1 v2 v3 v4”
local i=1
foreach var in `p’ {
if “`i'”==”1” {
local ttp “`””`var'””‘”
local ttpcomma “”`””`var'””‘””
else if “`i'”~=”1” {
local ttp  “`ttp'””`” “`var'” “‘”
local ttpcomma `”`ttpcomma’,”`””`var'””‘” “‘

local i=`i’+1

display “`p'”
display `ttp’
display “`ttpcomma'”

At SSCC are some Stata programming essentials.

via Nick Cox

1. You want to look for ” as a literal character, not a delimiter.
2. Therefore compound double quotes `” “‘ must be used as delimiters.
replace tags = subinstr(tags, `”””‘, “”, .)
The awkward argument is
`” left compound double quote
” double quote to be taken literally
“‘ right compound double quote
A trick to avoid all this is to note that ” is char(34) [see
-asciiplot- from SSC for a cheat sheet] so that
replace tags = subinstr(tags, char(34), “”, .)

via Econometrics by Simulation: Remove a subset from a global – Stata.

local xyz a b c d e f g a b c d e
local a a b c
local b: subinstr local xyz  “`a'” “”, all word
local c : list retokenize b // not necessary but removes excess spaces
disp “`c'”

From Jeremy Nighohossian is a useful cheat sheet for macros:

I have split the commands into two types – cmd and oper. cmd is a command on a single macro while oper requires two macros.

local/global macname : list cmd macname
cmd       description         Example
uniq       Extracts the unique elements of the macro         uniq “A B C B” returns “A B C”
dups      Extracts the repeated elements of the macro     dups “A B C B” returns “B”
sort        Alphabetizes the elements of the macro              sort “A B C B” returns “A B B C”
sizeof    Returns the number of elements

local/global macname : list macro1 oper macro2
oper      description         Example
|              Returns the union of both macros            “A B C” | “A C D” returns “A B C D”
&             returns the intersection of both macros                “A B C” & “A C D” returns “A C”
–              returns elements of macro1 less the elements that are present in macro2            “A B C” – “A C D” returns “B”
==           tests whether macro1 is identical to macro2 regardless of order                “A B C” == “A C B” returns 1
===        tests whether macro1 is identical to macro2 including order         “A B C” == “A C B” returns 0
in            tests whether all elements of macro1 are present in macro2       “A B C” in “A C D E B” returns 1

About mkevane

Economist at Santa Clara University and Director of Friends of African Village Libraries.
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