st: 3 methods for converting a string date to Stata format

[Michael McCulloch <mm@pinest.org>]

I recently posted a question on how to separate a string date into Stata 
date. I would like to share the three methods which I've learned:

* 3 methods for converting a string date to Stata format
clear
input datedx
    19900417
    19880107
    19930407
    19880819
    19890127
end

* METHOD 1
tostring datedx, replace
generate str4 dxyr1= substr(datedx,1,4)
generate str2 dxmo1 = substr(datedx,5,6)
generate str2 dxda1 = substr(datedx,7,8)
destring dx*, replace
gen datedx1 = mdy(dxmo1, dxda1, dxyr1)
format datedx1 %d

* METHOD 2 (by Maarten Buis)
destring datedx, replace
gen int dxyr2 = floor(datedx/10000)
gen int dxmo2 = floor((datedx-dxyr2*10000)/100)
gen int dxda2 = datedx - dxyr2*10000 - dxmo2*100
gen datedx2 = mdy(dxmo2, dxda2, dxyr2)
format datedx2 %d

* METHOD 3 (by Nick Cox; first must run .ssc install todate)
* uses the dates as numbers (i.e. use -destring- first) then the floor 
function.
todate datedx, gen(datedx3) pattern(yyyymmdd)
format datedx3 %d
list datedx datedx1 datedx2 datedx3 in 1/5


Best wishes,
Michael


____________________________________

Michael McCulloch
Pine Street Clinic
Pine Street Foundation
124 Pine Street, San Anselmo, CA 94960-2674
tel     415.407.1357
fax     415.485.1065
email:  mm@pinest.org
web:    www.pinest.org
        www.pinestreetfoundation.org
        www.medepi.net/meta





*
*   For searches and help try:
*   http://www.stata.com/support/faqs/res/findit.html
*   http://www.stata.com/support/statalist/faq
*   http://www.ats.ucla.edu/stat/stata/