### Wednesday, March 15, 2006

## Re: st: RE: summing up digits and comparing to a check digit

I seem to be the only person who came across this problem for the first time... Thanks for all the contributions, very interesting indeed

Lia

Richard Atkins wrote:

>Rather than use the mod function I would recommend converting all your >values to formatted strings using the =string(varname, format) command >prior to extracting the digits. > >In general the mod function works well but I have come across datasets >where values that displayed in tables and lists as (for example) 0.7 >produced a '6' when I tried to extract the 'tenths' digit using >mod(int(varname*10),10). It turned out that the floating point >representation of this value in the dta file was actually 0.69999999 so >the mod function gave me exactly what I asked for rather than what I >actually wanted. > >Some examples of extracting digits in this way are available in my >digit preference functions at >http://www.richardatkins.co.uk/statistics/statabits.htm > >Regards > >Richard A. >richard.atkins@lshtm.ac.uk > > > > >>>>n.j.cox@durham.ac.uk 03/15/06 3:04 pm >>> >>>> >>>> >-pnrcheck- from SSC covers the Swedish case. > >In this case, look _inside_ the program >for some ideas. String functions are not >the only way. -mod()- is also useful. > >The authors of -pnrcheck- are two Italians >and a Welshman, just who you would expect >to be working on Swedish identifiers. > >Nick >n.j.cox@durham.ac.uk > >Lia Orfei > > > >>I have a variable that contains 7-digit numbers; the first >>digit is the >>remainder of the sum of the last six digits divided by 10 >>(check digit) >> >>example: 1030332 => 0+3+0+3+3+2=11/10=1+1 => check digit=1 >> 12050457 => 0+5+0+4+5+7=21/10=2+1 => check digit=1 >>and so on. >> >>Now I want to assess whther the check digit is correct for each >> >> >entry. > > >>How do I calculate the partial sum of the contents of this variable? >> >>Extra challenge: some of the numbers sum up to 10, 20 etc so >>the check >>digit is actually 0 and it does not appear in the data for >>some reason >>(example 50456 is correct becasue 5+0+4+5+6=20 so the remainder is >> >> >0). > > >>Any ideas?? I was thinking about using the string functions. >> >> > >* >* 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/ >* >* 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/ > > >

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* * 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/

Tag: statalist