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From |
"Eric G. Wruck" <ewruck@econalytics.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
RE: st: gen new variable from string variables |

Date |
Tue, 26 Apr 2005 10:26:28 -0400 |

Hi Nick: Thanks for the little tutorial. I had seen this true/false tool in answers before but didn't get it (& frankly, didn't bother to try). I can now envision making use of it -- thanks. Eric >Eric Wruck, Rafal Raciborski and Joseph Coveney made >overlapping suggestions that all solved the problem, >so there's almost nothing left to be said, but I'll >say it anyway. > >For the general problem, the main ideas that make >things easier are > >* looping over variables with -foreach- > >* using -substr()- or -index()- to look for substrings. > >My main comment is to emphasise a point tacit in most >answers: you can exploit Stata's treatment of true and >false directly in such problems, and not just indirectly. > >For example, > >gen OK = 0 > >qui foreach v of var icd* { > replace OK = OK + index(`v', "E11") >} > >keep if OK > >works because any non-zero sum in -OK- >is treated as true. Similarly, with >the innermost statement instead > > replace OK = OK + (substr(`v',1,3) == "E11") > >the parenthesised expression evaluates >to 0 or 1, and so the same trick will >work: the criterion is whether the sum is >non-zero (here, positive) or not. > >The "or" operator | naturally leads to >the same conclusion. > >It is largely a matter of taste whether >you do it this way or using lots of -if- >conditions. The -if- route perhaps is >closer to the way people actually >think about the question, but doing >it this way has a habit of growing on you. > >There is background at > >What is true and false in Stata? >http://www.stata.com/support/faqs/data/trueorfalse.html > >King, Belinda L > >> > I am wanting to create a variable that tells me whether the >> patient has an >> > ICD10 starting with E11. I am not interested in the numbers >> after the dots, >> > nor am I interested in any of the other ICD10 codes and I >> am wanting to drop >> > patients who do not have E11 in one of the ICD10 columns. I >> have tried >> > playing with foreach, but this side of things is new for me >> and I just keep >> > getting messages telling me the syntax is incorrect. I would greatly >> > appreciate any hints someone could give me, thank you in advance. >> > >> > +----------------------------------+ >> > | id icd10_1 icd10_2 icd10_3 | >> > |----------------------------------| >> > 1. | 1 K61.3 Z86.43 F05.9 | >> > 2. | 2 B95.8 Z06.2 Z86.43 | >> > 3. | 3 E11.69 R40.2 E11.9 | >> > 4. | 4 Z86.43 Z95.8 E87.6 | >> > 5. | 5 K59.0 K59.0 Z93.1 | >> > |----------------------------------| >> > 6. | 6 E11.65 E11.66 R63.4 | >> > 7. | 7 E11.22 E66.9 E11.23 | >> > 8. | 8 E11.9 E78.0 K63.50 | >> > 9. | 9 E78.0 E11.65 D50.9 | >> > 10. | 10 E11.65 K59.0 Z93.0 | >> > +----------------------------------+ >> > > >* >* 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/

**References**:**RE: st: gen new variable from string variables***From:*"Nick Cox" <n.j.cox@durham.ac.uk>

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