st: matcell option in tab command within a loop inside postfile

["Jenny Yu" <jennyyu@upei.ca>]

Dear all,


I have the following STATA code for extracting the maximum number of the
categories for each variable in my varlist:


use "h:\mydata.dta", clear


tempname memhold
postfile `memhold' str20 yvar maxm1  using temp, replace


foreach yvar of varlist * {


capture tab `yvar', matcell(m)
svmat m
egen maxm1=max(m1)


post `memhold' ("`yvar'")  (maxm1)
drop m1 maxm1
}


postclose `memhold'



If I open stata and run this do file. It does not run and error message
is: "matrix m not found" "r(111);"
However, after this error warning, if I type(notes: var1 is any of the
variables in my varlist):
 tab var1, matcell(m)
 svmat m


Not only these two lines are fine, but also this time, the above whole
postfile works perfectly.  But as soon as I close stata and open stata
again, run the do file, everything above repeats.


Does anyone know why I have to use "tab var1, matcell(m); svmat m;"
first, and then the whole postfile works just fine? Or there are some
other tricks here?


Thanks in advance,
Jenny







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