Mata included in foreach var

[Lau Amdi]

Hi everyone,

I'm trying to automatize/optimize the code used to create my primary table.
What I'm trying to do is to make a table for each of my explaining variables according to vaccination status (yes/no) with frequencies and percentages for each category and the combine them in a matrix that I will write to an excel file.

If I were to do this individually for each variable this would be the code (here with sex as an example):

estpost tab vac sex , nototal
matrix freq_sex=e(b)'
matrix perc_sex=e(colpct)'

matrix coljoinbyname freq_perc_sex = freq_sex perc_sex

mata
freq_perc_sex=st_matrix("freq_perc_sex")
freq_perc_sex=colshape(freq_perc_sex,4)
st_matrix("freq_perc_sex", freq_perc_sex)
end

mat list freq_perc_sex

This will give me an output exactly as I want it in my table.

However, I would like to do this in a loop naming each matrix freq_perc_`var'. I can't get it to work though. Any inputs on the following code?:

foreach var of varlist (sex education treatment) {
estpost tab vac `var' , nototal
matrix freq_`var'=e(b)'
matrix perc_`var'=e(colpct)'
matrix coljoinbyname freq_perc_`var' = freq_`var' perc_`var'
mata
freq_perc_`var'=st_matrix("freq_perc"_`var')
freq_perc=colshape(freq_perc,4)
st_matrix("freq_perc"_`var', freq_perc_`var')
 end

mat list freq_perc
}

I'm posting this in the Mata forum, as the latter code will work if I leave out the mata code but then I can't use the colshape.
How do I implement the ´var' in the st_matrix()? I guess this is where the problem is.

When running the code I get the following error

11. end
---Break---
r(1);
end of do-file
---Break---
r(1)

At the moment I'm unfortunately not able to produce a dataex example. I'm working on a secure server and it will take a while to re-write everything from the dataex output. If needed, I will gladly take the time to do so. Thank you very much for the help.

[Lau Amdi]

Updated with a very small dataset using dataex. I was not able to edit the first post. Sorry for that.

* Example generated by -dataex-. For more infor, type help dataex
clear
input float(id vac sex education treatment)
1 0 1 0 0
2 1 1 1 1
3 0 0 1 0
4 0 0 0 1
5 1 0 0 1
6 1 1 1 0
7 0 0 1 1
8 0 1 0 0
9 1 0 1 1
10 1 1 0 0
end

[William Lisowski]

If you want

• a block of Mata code terminated by end

to run within

• a Stata block surrounded by braces {} - typically a program, but in fact within any brace-enclosed block of code

you need to

• define your Mata code as a Mata function outside the brace-enclosed block
• call the Mata function within the brace-enclosed block

Even though your "end" is meant to terminate a Mata block, at the time Stata is parsing the loop, the fact that the "end" belongs to Mata and not to Stata is not recognized, and causes Stata to react incorrectly.

With that said, in your particular case you can, I think, avoid this by changing

mata
    freq_perc_`var'=st_matrix("freq_perc"_`var')
    freq_perc=colshape(freq_perc,4)
    st_matrix("freq_perc"_`var', freq_perc_`var')
end

to

mata: freq_perc_`var'=st_matrix("freq_perc"_`var')
mata: freq_perc=colshape(freq_perc,4)
mata: st_matrix("freq_perc"_`var', freq_perc_`var')

When I tested this change, I got a series of errors. I think this is what you want.

foreach var of varlist (sex education treatment) {
estpost tab vac `var' , nototal
matrix freq_`var'=e(b)'
matrix perc_`var'=e(colpct)'
matrix coljoinbyname freq_perc_`var' = freq_`var' perc_`var'

mata: freq_perc_`var'=st_matrix("freq_perc_`var'")
mata: freq_perc=colshape(freq_perc_`var',4)
mata: st_matrix("freq_perc_`var'", freq_perc_`var')

mat list freq_perc_`var'
}

[Lau Amdi]

Thank you so much, William. The solution you provided worked perfectly.
It didn't occur to me that that Stata could not differ 'end' and '}'. The 3 x mata: did the job!