You need to use quotes to evaluate the local and you need to use commas to separate the values. Here's an example using the auto data.

    sysuse auto
    vallist rep78, sep(,)
    tab foreign if inlist(rep78, `r(list)')



I'm using `ssc install vallist` to generate a list of applicable countries that outputs a macro something like:

r(list) : "32 36 348 392 410 76 112 152 156 203"  
Optionally, this can be returned separated by commas instead of spaces if it's helpful)

I then want to `tab` a variable if it has a country that is anywhere in that list.

Any thoughts on how to do this.
I'd like to use inlist, but I'd have to pass each country in manually like this


    Typing by hand works just fine
    tab health if inlist(country, 32, 36, 348,... 203)
    
    I'd like to do this
    tab health if inlist(country, r(list))

Perhaps, is there any way I can loop through each element in the list and apply a filter with a if statement?

Checking If against multiple values

You are much of the way there, but there are some misconceptions here too. 

You can't format a local macro in the sense that you can assign a format to a local macro. What you are doing is telling `display` to use a format in showing the value of that macro, but the macro itself is unaffected and the format doesn't stick. In fact the macro and the format are never associated in any strict sense; it's entirely a matter of the `display` command putting your instructions together, what to show and precisely how to show it. 

This is not fundamentally different from similar commands in many other languages. 

One solution is 

    loc number1 12.20645161
    loc number2  52.81451247
    di "number 1 is " %5.4f `number1' "and number 2 is " %5.4f `number2' 

Note that omitting the = signs assigns the numbers as string equivalents; there is no conversion to binary and back to decimal that way. The difference would not bite in this example. 

Further notes: 

1. Avoid `round()` here like the plague. The solution to formatting problems is a format, not a numeric operation. It will work much of the time, but it's not guaranteed. It won't guarantee exactly what you want always because almost all decimal numbers cannot be held exactly as binaries and that will bite sometimes. 

2. You can do this

        local nice1 : di %5.4f `number1' 
        local nice2 : di %5.4f `number2' 
        di "number 1 is `nice1' and number 2 is `nice2'" 

That doesn't assign a format either, but it is the string manipulation you seek. 

The way to think of it is: Macros hold strings. When you want to manipulate strings as strings, use string operations only. 


I'd like to have some pretty output that combines several local macros that have been formatted and put into a single line

I've tried multiple different configurations, but here's basically what I'd like


    loc number1 = 12.20645161
    loc number2 = 52.81451247
    di "something here"

Desired Output: "number 1 is 12.2065 and number 2 is 52.8145"

I can format a single local macro:

    di %12.4f `number1'

And I can concatenate two unformatted macros:

    di "number 1 is `number1' and number 2 is `number1'"

But can't seem to do both simultaneously.  Is there a way to format the macro early or do some inline formatting or append formatted strings to each other?


Display and concatenate formatted numbers as a string

Previous answer focuses helpfully on `cond()` but contains some minor errors. 

       loc avgIncDec = cond(`avginc' > 0, "increased", "decreased")

Note that Stata, like many other languages, uses `=` for assignment and `==` to test for equality. 


Is there a way to express this with a terser syntax



    if (`avgInc' > 0) {
    	loc avgIncDec = "increased"
    }
    else {
    	loc acgIncDec = "decreased"
    }

Something like an InlineIf (iif):



    loc avgInc = iif((`avgInc' > 0), "increased", "decreased")